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I'm trying to implement shadow mapping in legacy OpenGL (yes, I know it's deprecated but however), but it's not working right. Almost everything is black (see picture, in the lower left I added a view from the light source). I checked the depth texture and projection and everything seems correct for me.
I have a diffuse texture in Texture Unit 0 and the depth texture is in Texture Unit 1.
My initialization code:
void InitScene()
{
light1_projection = glm::ortho(-10.0f, 10.0f, -10.0f, 10.0f, 1.0f, 100.0f);
light1_view = glm::lookAt(glm::vec3(30.0f, 35.0f, 30.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
camera_projection = glm::perspective(glm::radians(45.0f), 1.333f, 1.0f, 300.0f);
camera_view = glm::lookAt(glm::vec3(0.0f, 30.0f, 20.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
bias = glm::mat4(
0.5f, 0.0f, 0.0f, 0.0f,
0.0f, 0.5f, 0.0f, 0.0f,
0.0f, 0.0f, 5.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f
);
glEnable(GL_CULL_FACE);
glEnable(GL_DEPTH_TEST);
glClearColor(0.2f, 0.2f, 1.0f, 1.0f);
LoadTexture(); // Loads the diffuse texture in TMU 0
InitShadowmapTexture();
}
void InitShadowmapTexture()
{
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &shadowmap_texture);
glBindTexture(GL_TEXTURE_2D, shadowmap_texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);
glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_LUMINANCE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
shadowmap_width, shadowmap_heigth, 0,
GL_DEPTH_COMPONENT, GL_FLOAT, nullptr);
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
glEnable(GL_TEXTURE_GEN_R);
glEnable(GL_TEXTURE_GEN_Q);
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
}
My render code:
void Render()
{
RenderShadowMap();
RenderNormalScene();
RenderNormalSceneLightView();
}
void DrawScene(const glm::mat4 &view, const glm::mat4 &projection)
{
const auto plane = glm::translate(view, glm::vec3(0.0f, 0.0f, 0.0f));
const auto cube1 = glm::translate(view, glm::vec3(0.0f, 3.0f, z)) *
glm::rotate(glm::mat4(1.0f), glm::radians(rotx), glm::vec3(1.0f, 0.0f, 0.0f)) *
glm::rotate(glm::mat4(1.0f), glm::radians(roty), glm::vec3(0.0f, 1.0f, 0.0f));
glMatrixMode(GL_PROJECTION);
glLoadMatrixf(glm::value_ptr(projection));
glMatrixMode(GL_MODELVIEW);
glLoadMatrixf(glm::value_ptr(view));
glActiveTexture(GL_TEXTURE1);
const auto planes = bias * light1_projection * light1_view;
glTexGenfv(GL_S, GL_EYE_PLANE, glm::value_ptr(glm::row(planes, 0)));
glTexGenfv(GL_T, GL_EYE_PLANE, glm::value_ptr(glm::row(planes, 1)));
glTexGenfv(GL_R, GL_EYE_PLANE, glm::value_ptr(glm::row(planes, 2)));
glTexGenfv(GL_Q, GL_EYE_PLANE, glm::value_ptr(glm::row(planes, 3)));
glMatrixMode(GL_MODELVIEW);
glLoadMatrixf(glm::value_ptr(plane));
DrawPlane(20.0f, 20.0f);
glMatrixMode(GL_MODELVIEW);
glLoadMatrixf(glm::value_ptr(cube1));
DrawCube(size, size, size);
}
void RenderNormalScene()
{
glActiveTexture(GL_TEXTURE1);
glEnable(GL_TEXTURE_2D);
glCullFace(GL_BACK);
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glViewport(0, 0, screen_width, screen_heigth);
glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
DrawScene(camera_view, camera_projection);
}
void RenderNormalSceneLightView()
{
glActiveTexture(GL_TEXTURE1);
glEnable(GL_TEXTURE_2D);
glEnable(GL_SCISSOR_TEST);
glScissor(0, 0, screen_width / 6, screen_heigth / 6);
glCullFace(GL_BACK);
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glViewport(0, 0, screen_width / 6, screen_heigth / 6);
glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
DrawScene(light1_view, light1_projection);
glDisable(GL_SCISSOR_TEST);
}
void RenderShadowMap()
{
glActiveTexture(GL_TEXTURE1);
glDisable(GL_TEXTURE_2D);
glCullFace(GL_FRONT);
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
glViewport(0, 0, shadowmap_width, shadowmap_heigth);
glClear(GL_DEPTH_BUFFER_BIT);
DrawScene(light1_view, light1_projection);
glActiveTexture(GL_TEXTURE1);
glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, shadowmap_width, shadowmap_heigth);
}
Do you have any ideas how to solve this issue?
You have set the bias value to
bias = glm::mat4(
0.5f, 0.0f, 0.0f, 0.0f,
0.0f, 0.5f, 0.0f, 0.0f,
0.0f, 0.0f, 5.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f
);
In row 2, column 2, you have set the value to 5.0f, instead of 0.5f. This has the effect of scaling the z value by 5 instead of by 0.5; thus your error.
The correct bias matrix is
bias = glm::mat4(
0.5f, 0.0f, 0.0f, 0.0f,
0.0f, 0.5f, 0.0f, 0.0f,
0.0f, 0.0f, 0.5f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f
);
I am learning OpenGL by glfw3 lib and I am using imgui to make a interesting application.
I want to make a little Engine or CAD tool.
Problem is I can not render what I want in a imgui window.
I searched google and found below links:
https://gamedev.stackexchange.com/questions/150214/render-in-a-imgui-window
https://gamedev.stackexchange.com/questions/140693/how-can-i-render-an-opengl-scene-into-an-imgui-window
I tried about two days and I have rendered a triangle in a imgui window.
However when I try to render content as this link(Tutorial and Code) shows me.
The box in imgui window won't spin!!!
I tried serial days and I am going to give up, I really need your help.
#define __abc__ is a value to test.
Xhader.h just is the header file in the tutorial, also .vs and .fs files.
the difference is tutorial uses glad.h and I use glew.h
#define __abc__
#define STB_IMAGE_IMPLEMENTATION
#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"
#include "Xhader.h"
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
GLFWwindow* Proinit();
void imguiSetup(GLFWwindow* window);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
int main()
{
GLFWwindow* window = Proinit();
imguiSetup(window);
int view3d_width = 100;
int view3d_height = 200;
// configure global opengl state
// -----------------------------
glEnable(GL_DEPTH_TEST);
// build and compile our shader zprogram
// ------------------------------------
Xhader ourShader("shader/vs.txt", "shader/fs.txt");
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
GLuint VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
GLuint VAO;
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
//--------------------------------------- FBO -----------------------------//
#ifdef __abc__
unsigned int fbo;
glGenFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
GLuint TOF;
glGenTextures(1, &TOF);
glBindTexture(GL_TEXTURE_2D, TOF);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 400, 300, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
#else
;
#endif
// load and create a texture
// -------------------------
unsigned int texture1, texture2;
// texture 1
// ---------
glGenTextures(1, &texture1);
glBindTexture(GL_TEXTURE_2D, texture1);
// set the texture wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
// set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// load image, create texture and generate mipmaps
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis.
std::string s1 = "resources/textures/container.jpg";
std::string s2 = "resources/textures/awesomeface.png";
unsigned char* data = stbi_load(s1.c_str(), &width, &height, &nrChannels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
// texture 2
// ---------
glGenTextures(1, &texture2);
glBindTexture(GL_TEXTURE_2D, texture2);
// set the texture wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
// set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// load image, create texture and generate mipmaps
data = stbi_load(s2.c_str(), &width, &height, &nrChannels, 0);
if (data)
{
// note that the awesomeface.png has transparency and thus an alpha channel, so make sure to tell OpenGL the data type is of GL_RGBA
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
// tell opengl for each sampler to which texture unit it belongs to (only has to be done once)
// -------------------------------------------------------------------------------------------
ourShader.use();
ourShader.setInt("texture1", 0);
ourShader.setInt("texture2", 1);
// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
#ifdef __abc__
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, TOF, 0);
#endif
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE) {
std::cout << "FRAMEBUFFER SUCCESS" << std::endl;
glViewport(0, 0, 400, 300);
// render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // also clear the depth buffer now!
// bind textures on corresponding texture units
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texture2);
// activate shader
ourShader.use();
// create transformations
glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
glm::mat4 view = glm::mat4(1.0f);
glm::mat4 projection = glm::mat4(1.0f);
float time = (float)glfwGetTime();
std::cout << time << std::endl;
model = glm::rotate(model,time , glm::vec3(0.5f, 1.0f, 0.0f));
view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
// retrieve the matrix uniform locations
unsigned int modelLoc = glGetUniformLocation(ourShader.ID, "model");
unsigned int viewLoc = glGetUniformLocation(ourShader.ID, "view");
// pass them to the shaders (3 different ways)
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, &view[0][0]);
// note: currently we set the projection matrix each frame,
//but since the projection matrix rarely changes it's often best practice
//to set it outside the main loop only once.
ourShader.setMat4("projection", projection);
// render box
glBindVertexArray(VAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
#ifdef __abc__
glBindFramebuffer(GL_FRAMEBUFFER, 0);
#endif
}
else {
std::cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << std::endl;
}
#ifdef __abc__
// Start the Dear ImGui frame
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplGlfw_NewFrame();
ImGui::NewFrame();
bool View_3D = true;
if (View_3D) {
ImGui::Begin("3D View", &View_3D);
view3d_height = ImGui::GetWindowSize().x;
view3d_width = ImGui::GetWindowSize().y;
ImVec2 pos = ImGui::GetCursorScreenPos();
ImGui::GetWindowDrawList()->AddImage(
(void*)TOF,
ImVec2(ImGui::GetCursorScreenPos()),
ImVec2(ImGui::GetCursorScreenPos().x + ImGui::GetWindowSize().x - 15,
ImGui::GetCursorScreenPos().y + ImGui::GetWindowSize().y - 35),
ImVec2(0, 1),
ImVec2(1, 0)
);
ImGui::End();
}
// input
// -----
processInput(window);
ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
// render
ImGui::Render();
int display_w, display_h;
glfwGetFramebufferSize(window, &display_w, &display_h);
glViewport(0, 0, display_w, display_h);
glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
glClear(GL_COLOR_BUFFER_BIT);
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
#endif
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
// optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
// glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return 0;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
// make sure the viewport matches the new window dimensions; note that width and
// height will be significantly larger than specified on retina displays.
glViewport(0, 0, width, height);
}
GLFWwindow* Proinit() {
//glfwSetErrorCallback(glfw_error_callback);
if (!glfwInit()) return (GLFWwindow*)1;
#ifdef __APPLE__
// GL 3.2 + GLSL 150
const char* glsl_version = "#version 150";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac
#else
const char* glsl_version = "#version 130";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
//glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only
//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // 3.0+ only
#endif
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Shader3D", NULL, NULL);
if (window == NULL) { std::cout << "Failed to create GLFW window" << std::endl; glfwTerminate(); return (GLFWwindow*)-1; }
glfwMakeContextCurrent(window);
//glfwSwapInterval(1); // Enable vsync
//glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
#if defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
bool err = glewInit() != GLEW_OK;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
bool err = gladLoadGL() == 0;
#else
bool err = false;
#endif
if (err) { fprintf(stderr, "Failed to initialize OpenGL loader!\n"); return (GLFWwindow*)1; }
return window;
}
void imguiSetup(GLFWwindow* window) {
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO(); (void)io;
//io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
//io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
ImGui::StyleColorsDark();
ImGui_ImplGlfw_InitForOpenGL(window, true); //Setup Platform bindings
#ifdef __APPLE__
ImGui_ImplOpenGL3_Init("#version 150"); //Setup Renderer bindings
#else
ImGui_ImplOpenGL3_Init("#version 130");
#endif
}
First, you should create a framebuffer and a texture like f_tex
glGenFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
f_tex = CreateTexture(512, 512, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, f_texture,
GLuint depthrenderbuffer;
glGenRenderbuffers(1, &depthrenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthrenderbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, 512, 512);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthrenderbuffer);
and then, give the pointer of f_tex to drawList->AddImage()
ImGui::Begin("Game Window");
ImVec2 pos = ImGui::GetCursorScreenPos();
ImDrawList* drawList = ImGui::GetWindowDrawList();
auto app = SSEngine::App::main;
uint f_tex = app->getFrameBuffer();
drawList->AddImage((void*)f_tex,
pos,
ImVec2(pos.x + 512, pos.y + 512),
ImVec2(0, 1),
ImVec2(1, 0));
ImGui::End();
example in my project:
https://i.stack.imgur.com/365De.png
I found a wonderful volume rendering tutorial on the internet:
volume rendering tutorial
. The sample code is written in Windows and since I am working on a Mac, I tried to write my own code according to my understanding. For now, my program just arranges the 2D frame from -1 to 1 in Z axis without applying alpha and blend. So if everything goes well, I should be able to see the first slice. However, when I run the program, I get something weird.
My code:
//
// VolumeRendering.cpp
// Volume_Rendering
//
// Created by HOBBY on 4/5/14.
// Copyright (c) 2014 Yihao Jiang. All rights reserved.
//
#include <GLTools.h>
#include <GL/glew.h>
#include <Opengl/gl.h>
#include <glut/glut.h>
#include <fstream>
#include "VolumeRendering.h"
#include <GLMatrixStack.h>
#include <GLFrustum.h>
#include <GLGeometryTransform.h>
int m_uImageCount;
int m_uImageWidth;
int m_uImageHeight;
GLuint* m_puTextureIDs;
GLMatrixStack modelViewMatrix;
GLMatrixStack projectionMatrix;
GLFrame cameraFrame;
GLFrustum viewFrustum;
GLBatch myBatch;
GLGeometryTransform transformPipeline;
GLShaderManager shaderManager;
void ChangeSize(int w, int h)
{
glViewport(0, 0, w, h);
GLdouble aspectRatio = (GLdouble)(w)/(GLdouble)(h);
if (w <= h)
{
viewFrustum.SetOrthographic(-1.0f, 1.0f, -(1.0f/aspectRatio), 1.0f/aspectRatio, -1.0f, 1.0f);
}
else
{
viewFrustum.SetOrthographic(-1.0f, 1.0f, -(1.0f * aspectRatio), 1.0f * aspectRatio, -1.0f, 1.0f);
}
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}
void SetupRC()
{
glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
shaderManager.InitializeStockShaders();
glEnable(GL_DEPTH_TEST);
const char* filePath = "/Users/WensarHobby/Documents/Codes/workspace/Volume_Rendering/Volume_Rendering/head256x256x109";
if(!InitTextures2D(filePath))
{
printf("InitTexture error");
}
}
bool InitTextures2D(const char* filePath)
{
std::fstream myFile;
myFile.open(filePath, std::ios::in | std::ios::binary);
m_uImageCount = 109;
m_uImageWidth = 256;
m_uImageHeight = 256;
// Holds the texuture IDs
m_puTextureIDs = new GLuint[m_uImageCount];
// Holds the luminance buffer
char* chBuffer = new char[m_uImageWidth * m_uImageHeight];
char* chRGBABuffer = new char[m_uImageWidth * m_uImageHeight * 4];
glGenTextures(m_uImageCount, (GLuint*)m_puTextureIDs);
// Read each frames and construct the texture
for( int nIndx = 0; nIndx < m_uImageCount; ++nIndx )
{
// Read the frame
myFile.read(chBuffer, m_uImageWidth*m_uImageHeight);
// Set the properties of the texture.
glBindTexture( GL_TEXTURE_2D, m_puTextureIDs[nIndx] );
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, m_uImageWidth, m_uImageHeight , 0,
GL_LUMINANCE, GL_UNSIGNED_BYTE,(GLvoid *) chBuffer);
glBindTexture( GL_TEXTURE_2D, 0 );
}
delete[] chBuffer;
delete[] chRGBABuffer;
return true;
}
void SpecialKeys(int key, int x, int y)
{
if(key == GLUT_KEY_UP)
{}
if (key == GLUT_KEY_DOWN)
{
}
if (key == GLUT_KEY_LEFT)
{
}
if (key == GLUT_KEY_RIGHT)
{
}
glutPostRedisplay();
}
void RenderScene(void)
{
static GLfloat vLightPos [] = { 1.0f, 1.0f, 0.0f };
static GLfloat vWhite [] = { 1.0f, 1.0f, 1.0f, 1.0f };
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
modelViewMatrix.PushMatrix();
M3DMatrix44f mCamera;
cameraFrame.GetCameraMatrix(mCamera);
modelViewMatrix.MultMatrix(mCamera);
for(int nIndx=0; nIndx <m_uImageCount;++nIndx)
{
glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
MakeQuads(nIndx);
glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
}
shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(),
vLightPos, vWhite, 0);
myBatch.Draw();
modelViewMatrix.PopMatrix();
glutSwapBuffers();
}
void MakeQuads(int quads_index)
{
myBatch.Begin(GL_QUADS, 4, 1);
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(quads_index, 0.0f, 0.0f);
myBatch.Vertex3f(-1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(quads_index, 1.0f, 0.0f);
myBatch.Vertex3f(1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(quads_index, 0.0f, 1.0f);
myBatch.Vertex3f(-1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(quads_index, 1.0f, 1.0f);
myBatch.Vertex3f(1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
myBatch.End();
}
void ShutdownRC(void)
{
glDeleteTextures(m_uImageCount, (GLuint*)m_puTextureIDs);
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
glutInitWindowSize(400, 400);
glutCreateWindow("Volume_Rendering");
glutReshapeFunc(ChangeSize);
glutSpecialFunc(SpecialKeys);
glutDisplayFunc(RenderScene);
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
SetupRC();
glutMainLoop();
ShutdownRC();
return 0;
}
And this is my weird result:
I am new to OpenGL and volume rendering, in my opinion, there should be something wrong with my use of the shader manager. But I am not so sure. Anyone can tell me where the problem is? Thank you very much.
Finally, I figure it out! I was right and the problem lies in function MultiTexCoord2f(). The first parameter of this function here should always be 0 rather than quads_index. No multitextures here!! The new code looks like this:
#include <GLTools.h>
#include <GL/glew.h>
#include <Opengl/gl.h>
#include <glut/glut.h>
#include <fstream>
#include "VolumeRendering.h"
#include <GLMatrixStack.h>
#include <GLFrustum.h>
#include <GLGeometryTransform.h>
int m_uImageCount;
int m_uImageWidth;
int m_uImageHeight;
GLuint* m_puTextureIDs;
GLMatrixStack modelViewMatrix;
GLMatrixStack projectionMatrix;
GLFrame cameraFrame;
GLFrame objectFrame;
GLFrustum viewFrustum;
GLBatch myBatch;
GLGeometryTransform transformPipeline;
GLShaderManager shaderManager;
void ChangeSize(int w, int h)
{
glViewport(0, 0, w, h);
viewFrustum.SetPerspective(35.0f, float(w) / float(h), 1.0f, 500.0f);
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}
void SetupRC()
{
glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
shaderManager.InitializeStockShaders();
glEnable(GL_DEPTH_TEST);
const char* filePath = "/Users/WensarHobby/Documents/Codes/workspace/Volume_Rendering/Volume_Rendering/head256x256x109";
if(!InitTextures2D(filePath))
{
printf("InitTexture error");
}
cameraFrame.MoveForward(-7.0f);
}
bool InitTextures2D(const char* filePath)
{
std::fstream myFile;
myFile.open(filePath, std::ios::in | std::ios::binary);
m_uImageCount = 109;
m_uImageWidth = 256;
m_uImageHeight = 256;
// Holds the texuture IDs
m_puTextureIDs = new GLuint[m_uImageCount];
// Holds the luminance buffer
char* chBuffer = new char[m_uImageWidth * m_uImageHeight];
//char* chRGBABuffer = new char[m_uImageWidth * m_uImageHeight * 4];
glGenTextures(m_uImageCount, m_puTextureIDs);
// Read each frames and construct the texture
for( int nIndx = 0; nIndx < m_uImageCount; ++nIndx )
{
// Read the frame
myFile.read(chBuffer, m_uImageWidth*m_uImageHeight);
// Set the properties of the texture.
glBindTexture( GL_TEXTURE_2D, m_puTextureIDs[nIndx] );
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, m_uImageWidth, m_uImageHeight , 0,
GL_LUMINANCE, GL_UNSIGNED_BYTE,(GLvoid *) chBuffer);
glBindTexture( GL_TEXTURE_2D, 0 );
}
delete[] chBuffer;
// delete[] chRGBABuffer;
return true;
}
void SpecialKeys(int key, int x, int y)
{
glutPostRedisplay();
}
void RenderScene(void)
{
static GLfloat vLightPos [] = { 1.0f, 1.0f, 0.0f };
static GLfloat vWhite [] = { 1.0f, 1.0f, 1.0f, 1.0f };
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
modelViewMatrix.PushMatrix();
M3DMatrix44f mCamera;
cameraFrame.GetCameraMatrix(mCamera);
modelViewMatrix.MultMatrix(mCamera);
M3DMatrix44f mObjectFrame;
objectFrame.GetMatrix(mObjectFrame);
modelViewMatrix.MultMatrix(mObjectFrame);
for(int nIndx=0; nIndx <m_uImageCount;++nIndx)
{
glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
MakeQuads(nIndx);
glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(),
vLightPos, vWhite, 0);
myBatch.Draw();
}
modelViewMatrix.PopMatrix();
glutSwapBuffers();
}
void MakeQuads(int quads_index)
{
myBatch.Begin(GL_QUADS, 4, 1);
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
myBatch.Vertex3f(-1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
//myBatch.Vertex3f(-1.0f, -1.0f, 1.0f);
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(0, 1.0f, 0.0f);
myBatch.Vertex3f(1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
//myBatch.Vertex3f(1.0f, -1.0f, 1.0f);
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
myBatch.Vertex3f(1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
//myBatch.Vertex3f(1.0f, 1.0f, 1.0f);
myBatch.Normal3f(0.0f, 0.0f, -1.0f);
myBatch.MultiTexCoord2f(0, 0.0f, 1.0f);
myBatch.Vertex3f(-1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
//myBatch.Vertex3f(-1.0f, 1.0f, 1.0f);
myBatch.End();
}
void ShutdownRC(void)
{
glDeleteTextures(m_uImageCount, (GLuint*)m_puTextureIDs);
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
glutInitWindowSize(400, 400);
glutCreateWindow("Volume_Rendering");
glutReshapeFunc(ChangeSize);
glutSpecialFunc(SpecialKeys);
glutDisplayFunc(RenderScene);
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
SetupRC();
glutMainLoop();
ShutdownRC();
return 0;
}
I am trying to learn about using OpenGL with the 4th edition of OpenGL Super Bible, but whenever I try to copy one of the example codes in Visual Studio 2010, I get a "Open_GL.exe -System Error: The program can't start because libGLESv2.dll is missing from your computer".
I do have this .dll somewhere on my computer, but don't know how to make it available towards VS. The pre-built binaries on the site do work however.
The code I used, for reference:
// Block.cpp
// OpenGL SuperBible, Chapter 1
// Demonstrates an assortment of basic 3D concepts
// Program by Richard S. Wright Jr.
#include "../../shared/gltools.h" // OpenGL toolkit
#include "../../shared/math3d.h"
#include <math.h>
// Keep track of effects step
int nStep = 0;
// Lighting data
GLfloat lightAmbient[] = { 0.2f, 0.2f, 0.2f, 1.0f };
GLfloat lightDiffuse[] = { 0.7f, 0.7f, 0.7f, 1.0f };
GLfloat lightSpecular[] = { 0.9f, 0.9f, 0.9f };
GLfloat materialColor[] = { 0.8f, 0.0f, 0.0f };
GLfloat vLightPos[] = { -80.0f, 120.0f, 100.0f, 0.0f };
GLfloat ground[3][3] = { { 0.0f, -25.0f, 0.0f },
{ 10.0f, -25.0f, 0.0f },
{ 10.0f, -25.0f, -10.0f } };
GLuint textures[4];
// Called to draw scene
void RenderScene(void)
{
M3DMatrix44f mCubeTransform;
M3DVector4f pPlane;
// Clear the window with current clearing color
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glShadeModel(GL_SMOOTH);
glEnable(GL_NORMALIZE);
glPushMatrix();
// Draw plane that the cube rests on
glDisable(GL_LIGHTING);
if(nStep == 5)
{
glColor3ub(255,255,255);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, textures[0]);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-100.0f, -25.3f, -100.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-100.0f, -25.3f, 100.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(100.0f, -25.3f, 100.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(100.0f, -25.3f, -100.0f);
glEnd();
}
else
{
glColor3f(0.0f, 0.0f, 0.90f); // Blue
glBegin(GL_QUADS);
glVertex3f(-100.0f, -25.3f, -100.0f);
glVertex3f(-100.0f, -25.3f, 100.0f);
glVertex3f(100.0f, -25.3f, 100.0f);
glVertex3f(100.0f, -25.3f, -100.0f);
glEnd();
}
// Set drawing color to Red
glColor3f(1.0f, 0.0f, 0.0f);
// Enable, disable lighting
if(nStep > 2)
{
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glEnable(GL_COLOR_MATERIAL);
glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, lightSpecular);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glMaterialfv(GL_FRONT, GL_SPECULAR,lightSpecular);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, materialColor);
glMateriali(GL_FRONT, GL_SHININESS,128);
}
// Move the cube slightly forward and to the left
glTranslatef(-10.0f, 0.0f, 10.0f);
switch(nStep)
{
// Just draw the wire framed cube
case 0:
glutWireCube(50.0f);
break;
// Same wire cube with hidden line removal simulated
case 1:
// Front Face (before rotation)
glBegin(GL_LINES);
glVertex3f(25.0f,25.0f,25.0f);
glVertex3f(25.0f,-25.0f,25.0f);
glVertex3f(25.0f,-25.0f,25.0f);
glVertex3f(-25.0f,-25.0f,25.0f);
glVertex3f(-25.0f,-25.0f,25.0f);
glVertex3f(-25.0f,25.0f,25.0f);
glVertex3f(-25.0f,25.0f,25.0f);
glVertex3f(25.0f,25.0f,25.0f);
glEnd();
// Top of cube
glBegin(GL_LINES);
// Front Face
glVertex3f(25.0f,25.0f,25.0f);
glVertex3f(25.0f,25.0f,-25.0f);
glVertex3f(25.0f,25.0f,-25.0f);
glVertex3f(-25.0f,25.0f,-25.0f);
glVertex3f(-25.0f,25.0f,-25.0f);
glVertex3f(-25.0f,25.0f,25.0f);
glVertex3f(-25.0f,25.0f,25.0f);
glVertex3f(25.0f,25.0f,25.0f);
glEnd();
// Last two segments for effect
glBegin(GL_LINES);
glVertex3f(25.0f,25.0f,-25.0f);
glVertex3f(25.0f,-25.0f,-25.0f);
glVertex3f(25.0f,-25.0f,-25.0f);
glVertex3f(25.0f,-25.0f,25.0f);
glEnd();
break;
// Uniform colored surface, looks 2D and goofey
case 2:
glutSolidCube(50.0f);
break;
case 3:
glutSolidCube(50.0f);
break;
// Draw a shadow with some lighting
case 4:
glGetFloatv(GL_MODELVIEW_MATRIX, mCubeTransform);
glutSolidCube(50.0f);
glPopMatrix();
// Disable lighting, we'll just draw the shadow as black
glDisable(GL_LIGHTING);
glPushMatrix();
m3dGetPlaneEquation(pPlane, ground[0], ground[1], ground[2]);
m3dMakePlanarShadowMatrix(mCubeTransform, pPlane, vLightPos);
//MakeShadowMatrix(ground, lightpos, cubeXform);
glMultMatrixf(mCubeTransform);
glTranslatef(-10.0f, 0.0f, 10.0f);
// Set drawing color to Black
glColor3f(0.0f, 0.0f, 0.0f);
glutSolidCube(50.0f);
break;
case 5:
glColor3ub(255,255,255);
glGetFloatv(GL_MODELVIEW_MATRIX, mCubeTransform);
// Front Face (before rotation)
glBindTexture(GL_TEXTURE_2D, textures[1]);
glBegin(GL_QUADS);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(25.0f,25.0f,25.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(25.0f,-25.0f,25.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-25.0f,-25.0f,25.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-25.0f,25.0f,25.0f);
glEnd();
// Top of cube
glBindTexture(GL_TEXTURE_2D, textures[2]);
glBegin(GL_QUADS);
// Front Face
glTexCoord2f(0.0f, 0.0f);
glVertex3f(25.0f,25.0f,25.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(25.0f,25.0f,-25.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(-25.0f,25.0f,-25.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-25.0f,25.0f,25.0f);
glEnd();
// Last two segments for effect
glBindTexture(GL_TEXTURE_2D, textures[3]);
glBegin(GL_QUADS);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(25.0f,25.0f,-25.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(25.0f,-25.0f,-25.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(25.0f,-25.0f,25.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(25.0f,25.0f,25.0f);
glEnd();
glPopMatrix();
// Disable lighting, we'll just draw the shadow as black
glDisable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
glPushMatrix();
m3dGetPlaneEquation(pPlane, ground[0], ground[1], ground[2]);
m3dMakePlanarShadowMatrix(mCubeTransform, pPlane, vLightPos);
glMultMatrixf(mCubeTransform);
glTranslatef(-10.0f, 0.0f, 10.0f);
// Set drawing color to Black
glColor3f(0.0f, 0.0f, 0.0f);
glutSolidCube(50.0f);
break;
}
glPopMatrix();
// Flush drawing commands
glutSwapBuffers();
}
// This function does any needed initialization on the rendering
// context.
void SetupRC()
{
GLbyte *pBytes;
GLint nWidth, nHeight, nComponents;
GLenum format;
// Black background
glClearColor(0.0f, 0.0f, 0.0f, 1.0f );
glTexEnvi(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE, GL_MODULATE);
glGenTextures(4, textures);
// Load the texture objects
pBytes = gltLoadTGA("floor.tga", &nWidth, &nHeight, &nComponents, &format);
glBindTexture(GL_TEXTURE_2D, textures[0]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexImage2D(GL_TEXTURE_2D,0,nComponents,nWidth, nHeight, 0,
format, GL_UNSIGNED_BYTE, pBytes);
free(pBytes);
pBytes = gltLoadTGA("Block4.tga", &nWidth, &nHeight, &nComponents, &format);
glBindTexture(GL_TEXTURE_2D, textures[1]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexImage2D(GL_TEXTURE_2D,0,nComponents,nWidth, nHeight, 0,
format, GL_UNSIGNED_BYTE, pBytes);
free(pBytes);
pBytes = gltLoadTGA("block5.tga", &nWidth, &nHeight, &nComponents, &format);
glBindTexture(GL_TEXTURE_2D, textures[2]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexImage2D(GL_TEXTURE_2D,0,nComponents,nWidth, nHeight, 0,
format, GL_UNSIGNED_BYTE, pBytes);
free(pBytes);
pBytes = gltLoadTGA("block6.tga", &nWidth, &nHeight, &nComponents, &format);
glBindTexture(GL_TEXTURE_2D, textures[3]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexImage2D(GL_TEXTURE_2D,0,nComponents,nWidth, nHeight, 0,
format, GL_UNSIGNED_BYTE, pBytes);
free(pBytes);
}
void KeyPressFunc(unsigned char key, int x, int y)
{
if(key == 32)
{
nStep++;
if(nStep > 5)
nStep = 0;
}
// Refresh the Window
glutPostRedisplay();
}
void ChangeSize(int w, int h)
{
// Calculate new clipping volume
GLfloat windowWidth;
GLfloat windowHeight;
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if(h == 0)
h = 1;
// Keep the square square
if (w <= h)
{
windowHeight = 100.0f*(GLfloat)h/(GLfloat)w;
windowWidth = 100.0f;
}
else
{
windowWidth = 100.0f*(GLfloat)w/(GLfloat)h;
windowHeight = 100.0f;
}
// Set the viewport to be the entire window
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// Set the clipping volume
glOrtho(-100.0f, windowWidth, -100.0f, windowHeight, -200.0f, 200.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glLightfv(GL_LIGHT0,GL_POSITION, vLightPos);
glRotatef(30.0f, 1.0f, 0.0f, 0.0f);
glRotatef(330.0f, 0.0f, 1.0f, 0.0f);
}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glutInitWindowSize(800, 600);
glutCreateWindow("3D Effects Demo");
glutReshapeFunc(ChangeSize);
glutKeyboardFunc(KeyPressFunc);
glutDisplayFunc(RenderScene);
SetupRC();
glutMainLoop();
glDeleteTextures(4,textures);
return 0;
}
I do have this .dll somewhere on my computer
libGLESv2.dll sounds suspiciously like an implementation of OpenGL ES 2.0. Which will not execute your code, since your code is written for desktop OpenGL.
In short, you are linking to the wrong library. On Windows, you should be linking to OpenGL32.lib.
I created 4 textures and attach them to FBO, named fbo_texture0 - fbo_texture3. All of them are successfully created, as given by the following screenshot:
image 1
Now, i wanted to create the 5th texture which is obtained from the previous textures (fbo_texture0 - fbo_texture3) using GLSL. For now, i just want to copy the first texture into the fifth texture. Unfortunately, here is what i got:
image 2
The question is:
How can i access these fbo textures in GLSL?
How can i create the 5th texture? (or copy from the first texture to the fifth texture?)
Here's the complete code of the program (in case needed):
#include <windows.h>
#include <GL/glew.h> // Include the GLEW header file
#include <GL/glut.h> // Include the GLUT header file
#include <iostream> // Allow us to print to the console
using namespace std;
bool* keyStates = new bool[256]; // Create an array of boolean values of length 256 (0-255)
unsigned int fbo; // The frame buffer object
unsigned int fbo_depth; // The depth buffer for the frame buffer object
unsigned int fbo_texture0; // The texture object to write our frame buffer object to
unsigned int fbo_texture1;
unsigned int fbo_texture2;
unsigned int fbo_texture3;
unsigned int fbo_texture4;
GLhandleARB shaderProgram;
GLhandleARB vertexShader;
GLhandleARB fragmentShader;
int window_width = 500; // The width of our window
int window_height = 500; // The height of our window
void initFrameBufferDepthBuffer(void) {
glGenRenderbuffers(1, &fbo_depth); // Generate one render buffer and store the ID in fbo_depth
glBindRenderbuffer(GL_RENDERBUFFER, fbo_depth); // Bind the fbo_depth render buffer
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, window_width, window_height); // Set the render buffer storage to be a depth component, with a width and height of the window
glBindRenderbuffer(GL_RENDERBUFFER, 0); // Unbind the render buffer
}
void initFrameBufferTextures(void) {
glGenTextures(1, &fbo_texture0); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture0); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture1); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture1); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture2); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture2); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture3); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture3); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture4); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture4); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
}
void printInfoLog(GLhandleARB obj)
{
int infologLength = 0;
int charsWritten = 0;
char* infoLog;
glGetObjectParameterivARB(obj, GL_OBJECT_INFO_LOG_LENGTH_ARB, &infologLength);
if (infologLength > 0)
{
infoLog = (char*)malloc(infologLength);
glGetInfoLogARB(obj, infologLength, &charsWritten, infoLog);
printf("%s\n",infoLog);
free(infoLog);
}
}
void initFrameBuffer(void) {
initFrameBufferDepthBuffer(); // Initialize our frame buffer depth buffer
initFrameBufferTextures(); // Initialize our frame buffer ture
glGenFramebuffers(1, &fbo); // Generate one frame buffer and store the ID in fbo
glBindFramebuffer(GL_FRAMEBUFFER, fbo); // Bind our frame buffer
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_texture0, 0);// Attach the ture fbo_texturen to the color buffer in our frame buffer
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, fbo_texture1, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, fbo_texture2, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT3, GL_TEXTURE_2D, fbo_texture3, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT4, GL_TEXTURE_2D, fbo_texture4, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, fbo_depth); // Attach the depth buffer fbo_depth to our frame buffer
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER); // Check that status of our generated frame buffer
if (status != GL_FRAMEBUFFER_COMPLETE) // If the frame buffer does not report back as complete
{
cout << "Couldn't create frame buffer" << endl; // Output an error to the console
exit(0); // Exit the application
}
glBindFramebuffer(GL_FRAMEBUFFER, 0); // Unbind our frame buffer
}
void init(void) {
//glEnable(GL_TEXTURE_2D); // Enable turing so we can bind our frame buffer ture
glEnable(GL_DEPTH_TEST); // Enable depth testing
initFrameBuffer(); // Create our frame buffer object
}
void keyOperations (void) {
if (keyStates['a']) { // If the a key has been pressed
// Perform 'a' key operations
}
}
void renderTextures(void) {
glBindFramebuffer(GL_FRAMEBUFFER, fbo); // Bind our frame buffer for rendering
glPushAttrib(GL_VIEWPORT_BIT | GL_ENABLE_BIT); // Push our glEnable and glViewport states
glViewport(0, 0, window_width, window_height); // Set the size of the frame buffer view port
glDrawBuffer(GL_COLOR_ATTACHMENT0);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -5.0f);
//Add ambient light
GLfloat ambientColor[] = {0.2f, 0.2f, 0.2f, 1.0f}; //Color(0.2, 0.2, 0.2)
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientColor);
//Add positioned light
GLfloat lightColor0[] = {0.5f, 0.5f, 0.5f, 1.0f}; //Color (0.5, 0.5, 0.5)
GLfloat lightPos0[] = {4.0f, 0.0f, 8.0f, 1.0f}; //Positioned at (4, 0, 8)
glLightfv(GL_LIGHT0, GL_DIFFUSE, lightColor0);
glLightfv(GL_LIGHT0, GL_POSITION, lightPos0);
//Add directed light
GLfloat lightColor1[] = {0.5f, 0.2f, 0.2f, 1.0f}; //Color (0.5, 0.2, 0.2)
//Coming from the direction (-1, 0.5, 0.5)
GLfloat lightPos1[] = {-1.0f, 0.5f, 0.5f, 0.0f};
glLightfv(GL_LIGHT1, GL_DIFFUSE, lightColor1);
glLightfv(GL_LIGHT1, GL_POSITION, lightPos1);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_LIGHT1);
glEnable(GL_DEPTH_TEST);
glutSolidTeapot(2.0);
glColor3f(0.1,0.2,0.7);
glDrawBuffer(GL_COLOR_ATTACHMENT1);
glClearColor(0.5f, 0.5f, 0.0f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -5.0f);
glutSolidTorus(0.80, 1.6, 50, 100);
glColorMaterial ( GL_FRONT_AND_BACK, GL_EMISSION ) ;
glEnable ( GL_COLOR_MATERIAL ) ;
glDrawBuffer(GL_COLOR_ATTACHMENT2);
glClearColor(0.5f, 0.0f, 0.0f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -2.0f);
glutSolidTetrahedron();
glColorMaterial ( GL_FRONT_AND_BACK, GL_EMISSION ) ;
glEnable ( GL_COLOR_MATERIAL ) ;
glDrawBuffer(GL_COLOR_ATTACHMENT3);
glClearColor(0.5f, 0.0f, 0.3f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -2.0f);
glutSolidOctahedron();
glColorMaterial ( GL_FRONT_AND_BACK, GL_EMISSION ) ;
glEnable ( GL_COLOR_MATERIAL ) ;
glBindFramebuffer(GL_FRAMEBUFFER, 0); // Unbind our ture
glActiveTexture(GL_TEXTURE0);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture0);
glUniform1i(glGetUniformLocation(shaderProgram, "tex0"), 0);
glActiveTexture(GL_TEXTURE1);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture1);
glUniform1i(glGetUniformLocation(shaderProgram, "tex1"), 1);
glActiveTexture(GL_TEXTURE2);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture2);
glUniform1i(glGetUniformLocation(shaderProgram, "tex2"), 2);
glActiveTexture(GL_TEXTURE3);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture3);
glUniform1i(glGetUniformLocation(shaderProgram, "tex3"), 3);
glPopAttrib(); // Restore our glEnable and glViewport states
glutSwapBuffers();
}
static char* textFileRead(const char *fileName) {
char* text;
if (fileName != NULL) {
FILE *file = fopen(fileName, "rt");
if (file != NULL) {
fseek(file, 0, SEEK_END);
int count = ftell(file);
rewind(file);
if (count > 0) {
text = (char*)malloc(sizeof(char) * (count + 1));
count = fread(text, sizeof(char), count, file);
text[count] = '\0';
}
fclose(file);
}
}
return text;
}
void initShader(){
char* vsSource = textFileRead("./shader/multitexture.vs");
char* fsSource = textFileRead("./shader/multitexture.fs");
printf("%s\n",fsSource);
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, (const GLchar **)(&vsSource), NULL);
glCompileShader(vertexShader);
printInfoLog(vertexShader);
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, (const GLchar **)(&fsSource), NULL);
glCompileShader(fragmentShader);
printInfoLog(fragmentShader);
delete [] vsSource;
delete [] fsSource;
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
}
void display (void) {
keyOperations(); // Perform any key presses
glUseProgram(0);
renderTextures(); // Render our teapot scene into our frame buffer
GLsync s = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
glUseProgram(shaderProgram);
glClearColor(0.0f, 1.0f, 0.0f, 1.0f); // Clear the background of our window to red
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //Clear the colour buffer (more buffers later on)
glLoadIdentity(); // Load the Identity Matrix to reset our drawing locations
glTranslatef(-4.7f, 1.0f, -4.0f);
glWaitSync(s, 0, GL_TIMEOUT_IGNORED);
glDeleteSync(s);
glBindTexture(GL_TEXTURE_2D, fbo_texture0); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(-2.5f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture1); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(-0.3f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture2); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(1.9f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture3); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(4.1f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture4); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glutSwapBuffers();
}
void reshape (int width, int height) {
glViewport(0, 0, (GLsizei)width, (GLsizei)height); // Set our viewport to the size of our window
glMatrixMode(GL_PROJECTION); // Switch to the projection matrix so that we can manipulate how our scene is viewed
glLoadIdentity(); // Reset the projection matrix to the identity matrix so that we don't get any artifacts (cleaning up)
gluPerspective(60, (GLfloat)width / (GLfloat)height, 1.0, 100.0); // Set the Field of view angle (in degrees), the aspect ratio of our window, and the new and far planes
glMatrixMode(GL_MODELVIEW); // Switch back to the model view matrix, so that we can start drawing shapes correctly
}
void keyPressed (unsigned char key, int x, int y) {
keyStates[key] = true; // Set the state of the current key to pressed
}
void keyUp (unsigned char key, int x, int y) {
keyStates[key] = false; // Set the state of the current key to not pressed
}
int main (int argc, char **argv) {
glutInit(&argc, argv); // Initialize GLUT
glutInitDisplayMode (GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA); // Set up a basic display buffer (only single buffered for now)
glutInitWindowSize (1280, 500); // Set the width and height of the window
glutInitWindowPosition (100, 100); // Set the position of the window
glutCreateWindow ("OpenGL FBO"); // Set the title for the window
if (GLEW_OK != glewInit()) {
std::cout << "Couldn't initialize GLEW" << std::endl;
exit(0);
}
initShader();
init();
glutDisplayFunc(display); // Tell GLUT to use the method "display" for rendering
glutIdleFunc(display); // Tell GLUT to use the method "display" for rendering
glutReshapeFunc(reshape); // Tell GLUT to use the method "reshape" for reshaping
glutKeyboardFunc(keyPressed); // Tell GLUT to use the method "keyPressed" for key presses
glutKeyboardUpFunc(keyUp); // Tell GLUT to use the method "keyUp" for key up events
glutMainLoop(); // Enter GLUT's main loop
}
Here is the vertex shader:
void main(void)
{
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_Position = ftransform();
}
And here is the fragment shader:
uniform sampler2D tex0;
uniform sampler2D tex1;
uniform sampler2D tex2;
uniform sampler2D tex3;
void main(void)
{
gl_FragColor = texture2D(tex0, gl_TexCoord[0].st);
}
EDIT #1
After modifying the code as suggested by #Damon (the code has been edited as well) , here's the screenshot of the result:
image 3
Now, I don't really know what the problem actually is. I tried to change the fragment shader to access another texture e.g. gl_FragColor = texture2D(tex2, gl_TexCoord[0].st); but i still got the same display as above. So i think it is definitely not the modelview/projection problem.
EDIT #2
The problem still left unclear. However, I tried to give only one glActiveTexture(GL_TEXTUREn); command at the program, and comment out other glActiveTexture command (without shader modification), and got the following result:
image 4 Only glActiveTexture(GL_TEXTURE0);activated.
image 5 Only glActiveTexture(GL_TEXTURE1);activated.
image 6 Only glActiveTexture(GL_TEXTURE2);activated.
image 7 Only glActiveTexture(GL_TEXTURE3);activated.
When at least 2 glActiveTexture(GL_TEXTUREn); activated, i got the same result as image 5. That left me wondering what the problem actually is.
initShader compiles and links a shader. You seem to be binding the textures to texture units within renderTextures in an OK manner, too (after unbinding the FBO, which is important to sync). So far so good, but I can't find glUseProgram anywhere in the code. That would mean the rendering falls back to fixed function, which does not have any textures bound at that time.
The fragment shader reads only from tex0, so of course you wouldn't expect to see tex1-tex3 anyway (but I guess that's just the minimum working example code).
Other than that, it looks OK from what I can see by reading over the code in 5 mins.
(As a sidenote: init calls glEnable(GL_TEXTURE_2D), this is not strictly wrong, but useless as soon as you use a shader, see this.)
How about this:
glBindFramebuffer(GL_FRAMEBUFFER, fbo); // Bind our frame buffer for rendering
glDrawBuffer(GL_COLOR_ATTACHMENT4);
glBindTexture(GL_TEXTURE_2D, fbo_texture0); // bind texture that is rendered in 0-th attachment
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
You just render into 4th attachment with binded texture from 0-th attachment.