GLSL compiler can't find cameraPosition definition? - c++

Question

I am trying to build a code that uses OpenGL and shaders that adds texture to a square pyramid. After I added the functions to add the texture, ran the code but instead of rendering, I get a console window giving me the following error:
INFO: OpenGL Version: 4.4.0 NVIDIA 512.15
ERROR::SHADER::VERTEX::COMPILATION_FAILED
0(2) : error C1503: undefined variable "cameraPosition"
0(2) : error C1503: undefined variable "cameraPosition"
0(2) : error C1503: undefined variable "cameraPosition"
0(2) : error C1035: assignment of incompatible types
I have tried copying and pasting the cameraPosition variable from the bottom of my code to one of my main functions that has the gl_Position variable. But that did not solve the problem. Do I need to change the vec3 to vec4 somewhere or do I need to copy and paste the cameraPostion variable and definition somewhere else? Here is my code:
#include <iostream> // cout, cerr
#include <cstdlib> // EXIT_FAILURE
#include <GL/glew.h> // GLEW library
#include <GLFW/glfw3.h> // GLFW library
// GLM Math Header inclusions
#include <glm/glm.hpp>
#include <glm/gtx/transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <SOIL2.h> // SOIL2 library
using namespace std; // Standard namespace
/*Shader program Macro*/
#ifndef GLSL
#define GLSL(Version, Source) "#version " #Version " core \n" #Source
#endif
// Input Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void cursor_position_callback(GLFWwindow* window, double xpos, double ypos);
void mouse_button_callback(GLFWwindow* window, int button, int action, int mods);
// Declare View Matrix
glm::mat4 viewMatrix;
// Initialize FOV
GLfloat fov = 45.f;
// Define Camera Attributes
glm::vec3 cameraPosition = glm::vec3(0.f, 0.f, 3.f);
glm::vec3 target = glm::vec3(0.f, 0.f, 0.f);
glm::vec3 cameraDirection = glm::normalize(cameraPosition - target);
glm::vec3 worldUp = glm::vec3(0.f, 1.f, 0.f);
glm::vec3 cameraRight = glm::normalize(glm::cross(worldUp, cameraDirection));
glm::vec3 cameraUp = glm::normalize(glm::cross(cameraDirection, cameraRight));
glm::vec3 cameraFront = glm::normalize(glm::vec3(0.f, 0.f, -1.f));
// Declare target prototype
glm::vec3 getTarget();
// Camera transformation prototype
void TransformCamera();
// Boolean for keys and mouse buttons
bool keys[1024], mouseButtons[3];
// Boolean to check camera transformations
bool isPanning = false, isOrbiting = false;
// Radius, Pitch, and Yaw
GLfloat radius = 3.f, rawYaw = 0.f, rawPitch = 0.f, degYaw, degPitch;
GLfloat deltaTime = 0.f, lastFrame = 0.f;
GLfloat lastX = 400, lastY = 300, xChange, yChange;
bool firstMouseMove = true; // Detect inititial mouse movement
void initCamera();
// Unnamed namespace
namespace
{
const char* const WINDOW_TITLE = "Basic Camera Movement"; // Macro for window title
// Variables for window width and height
int WINDOW_WIDTH = 800;
int WINDOW_HEIGHT = 600;
// Stores the GL data relative to a given mesh
struct GLMesh
{
GLuint vao; // Handle for the vertex array object
GLuint vbos[2]; // Handles for the vertex buffer objects
GLuint nIndices; // Number of indices of the mesh
};
// Main GLFW window
GLFWwindow* gWindow = nullptr;
// Triangle mesh data
GLMesh gMesh;
// Shader program
GLuint gProgramId;
}
/* User-defined Function prototypes to:
* initialize the program, set the window size,
* redraw graphics on the window when resized,
* and render graphics on the screen
*/
bool UInitialize(int, char* [], GLFWwindow** window);
void UResizeWindow(GLFWwindow* window, int width, int height);
void UProcessInput(GLFWwindow* window);
void UCreateMesh(GLMesh& mesh);
void UDestroyMesh(GLMesh& mesh);
void URender();
bool UCreateShaderProgram(const char* vtxShaderSource, const char* fragShaderSource, GLuint& programId);
void UDestroyShaderProgram(GLuint programId);
/* Vertex Shader Source Code*/
const GLchar* vertexShaderSource = GLSL(440,
layout(location = 0) in vec3 position; // Vertex data from Vertex Attrib Pointer 0
layout(location = 1) in vec3 color; // Color data from Vertex Attrib Pointer 1
layout(location = 2) in vec2 texture; // Texture data from Vertex Attrib Pointer 2
out vec3 vertexColor; // variable to transfer color data to the fragment shader
out vec3 vertexTexture;
//Global variables for the transform matrices
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
uniform sampler2D myTexture; // Sampler
void main()
{
gl_Position = projection * view * model * vec4(cameraPosition.x, cameraPosition.y, cameraPosition.z, 1.0f); // transforms vertices to clip coordinates
vertexColor = color; // references incoming color data
vertexTexture = texture;
}
);
/* Fragment Shader Source Code*/
const GLchar* fragmentShaderSource = GLSL(440,
in vec3 vertexColor; // Variable to hold incoming color data from vertex shader
out vec3 fragmentColor;
out vec3 fragmentTexture;
void main()
{
fragmentColor = texture(myTexture, textTexture);
fragmentTexture = vec2(vertexTexture);
}
);
int main(int argc, char* argv[])
{
if (!UInitialize(argc, argv, &gWindow))
return EXIT_FAILURE;
// Create the mesh
UCreateMesh(gMesh); // Calls the function to create the Vertex Buffer Object
// Create the shader program
if (!UCreateShaderProgram(vertexShaderSource, fragmentShaderSource, gProgramId))
return EXIT_FAILURE;
// Sets the background color of the window to black (it will be implicitely used by glClear)
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
// Set input call back functions
glfwSetKeyCallback(gWindow, key_callback);
glfwSetCursorPosCallback(gWindow, cursor_position_callback);
glfwSetMouseButtonCallback(gWindow, mouse_button_callback);
glfwSetScrollCallback(gWindow, scroll_callback);
// render loop
// -----------
while (!glfwWindowShouldClose(gWindow))
{
// Set delta time
GLfloat currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
// Resize window and graphics simultaneously
glfwGetFramebufferSize(gWindow, &WINDOW_WIDTH, &WINDOW_HEIGHT);
// input
// -----
UProcessInput(gWindow);
// Render this frame
URender();
glfwPollEvents();
// Poll camera transformations
TransformCamera();
}
// Release mesh data
UDestroyMesh(gMesh);
// Release shader program
UDestroyShaderProgram(gProgramId);
exit(EXIT_SUCCESS); // Terminates the program successfully
}
// Initialize GLFW, GLEW, and create a window
bool UInitialize(int argc, char* argv[], GLFWwindow** window)
{
// GLFW: initialize and configure
// ------------------------------
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 4);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
// GLFW: window creation
// ---------------------
* window = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, WINDOW_TITLE, NULL, NULL);
if (*window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return false;
}
glfwMakeContextCurrent(*window);
glfwSetFramebufferSizeCallback(*window, UResizeWindow);
// GLEW: initialize
// ----------------
// Note: if using GLEW version 1.13 or earlier
glewExperimental = GL_TRUE;
GLenum GlewInitResult = glewInit();
if (GLEW_OK != GlewInitResult)
{
std::cerr << glewGetErrorString(GlewInitResult) << std::endl;
return false;
}
// Displays GPU OpenGL version
cout << "INFO: OpenGL Version: " << glGetString(GL_VERSION) << endl;
return true;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
void UProcessInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
float cameraSpeed = 2.5 * deltaTime;
if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
cameraPosition += cameraSpeed * cameraFront;
if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
cameraPosition -= cameraSpeed * cameraFront;
if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
cameraPosition -= glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
cameraPosition += glm::normalize(glm::cross(cameraFront, cameraUp)) * cameraSpeed;
if (glfwGetKey(window, GLFW_KEY_Q) == GLFW_PRESS)
cameraPosition -= cameraSpeed * cameraUp;
if (glfwGetKey(window, GLFW_KEY_E) == GLFW_PRESS)
cameraPosition += cameraSpeed * cameraUp;
}
// glfw: whenever the window size changed (by OS or user resize) this callback function executes
void UResizeWindow(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
// Functioned called to render a frame
void URender()
{
// Enable z-depth
glEnable(GL_DEPTH_TEST);
// Wireframe mode
// glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
// Clear the frame and z buffers
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// 1. Scales the object by 2
glm::mat4 scale = glm::scale(glm::vec3(1.0f, 1.0f, 1.0f));
// 2. Rotates shape by 15 degrees in the x axis
glm::mat4 rotation = glm::rotate(45.0f, glm::vec3(1.0, 1.0f, 1.0f));
// 3. Place object at the origin
glm::mat4 translation = glm::translate(glm::vec3(0.0f, 0.0f, 0.0f));
// Model matrix: transformations are applied right-to-left order
glm::mat4 model = translation * rotation * scale;
// Transforms the camera: move the camera back (z axis)
glm::mat4 view = glm::lookAt(cameraPosition, getTarget(), worldUp);
// Creates a perspective projection
glm::mat4 projection = glm::perspective(fov, (GLfloat)WINDOW_WIDTH / (GLfloat)WINDOW_HEIGHT, 0.1f, 100.0f);
// Set the shader to be used
glUseProgram(gProgramId);
// Retrieves and passes transform matrices to the Shader program
GLint modelLoc = glGetUniformLocation(gProgramId, "model");
GLint viewLoc = glGetUniformLocation(gProgramId, "view");
GLint projLoc = glGetUniformLocation(gProgramId, "projection");
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
GLuint crateTexture = {1};
glBindTexture(GL_TEXTURE_2D, crateTexture);
// Activate the VBOs contained within the mesh's VAO
glBindVertexArray(gMesh.vao);
// Draws the triangles
glDrawElements(GL_TRIANGLES, gMesh.nIndices, GL_UNSIGNED_SHORT, NULL); // Draws the triangle
// Deactivate the Vertex Array Object
glBindVertexArray(0);
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
glfwSwapBuffers(gWindow); // Flips the the back buffer with the front buffer every frame.
}
// Implements the UCreateMesh function
void UCreateMesh(GLMesh& mesh)
{
// Position and Color data
GLfloat verts[] = {
0.0f, 1.0f, 0.0f, // Top Center Vertex 0
1.0f, 0.0f, 0.0f, 1.0f, // Red
0.5f, 1.0f, // UV
-1.0f, -1.0f, 1.0f, // Bottom Left Vertex 1
0.0f, 1.0f, 0.0f, 1.0f, // Green
0.0f, 0.0f, // UV
1.0f, -1.0f, 1.0f, // Bottom Right Vertex 2
0.0f, 0.0f, 1.0f, 1.0f, // Blue
1.0f, 0.0f, // UV
1.0f, -1.0f, -1.0f, // Bottom Back Right Vertex 3
1.0f, 0.0f, 1.0f, 1.0f, // Magenta
0.0f, 0.0f, // UV
-1.0f, -1.0f, -1.0f, // Bottom Back Left Vertex 4
1.0f, 1.0f, 0.0f, 1.0f, // Yellow
1.0f, 0.0f // UV
};
// Index data to share position data
GLushort indices[] = {
// Sides
0, 1, 2, // Triangle 1
0 ,2, 3, // Triangle 2
0, 3, 1, // Triangle 3
0, 3, 4, // Triangle 4
// Base
1, 2, 3, // Triangle 5
1, 4, 3 // Triangle 6
};
const GLuint floatsPerVertex = 3;
const GLuint floatsPerColor = 4;
const GLuint floatsPerTexture = 2;
glGenVertexArrays(1, &mesh.vao); // we can also generate multiple VAOs or buffers at the same time
glBindVertexArray(mesh.vao);
// Create 2 buffers: first one for the vertex data; second one for the indices
glGenBuffers(2, mesh.vbos);
glBindBuffer(GL_ARRAY_BUFFER, mesh.vbos[0]); // Activates the buffer
glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW); // Sends vertex or coordinate data to the GPU
mesh.nIndices = sizeof(indices) / sizeof(indices[0]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh.vbos[1]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// Strides between vertex coordinates is 6 (x, y, z, r, g, b, a). A tightly packed stride is 0.
GLint stride = sizeof(float) * (floatsPerVertex + floatsPerColor);// The number of floats before each
// Create Vertex Attribute Pointers
glVertexAttribPointer(0, floatsPerVertex, GL_FLOAT, GL_FALSE, stride, 0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, floatsPerColor, GL_FLOAT, GL_FALSE, stride, (char*)(sizeof(float) * floatsPerVertex));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, floatsPerTexture, GL_FLOAT, GL_FALSE, stride, (char*)(sizeof(float) * floatsPerTexture));
glEnableVertexAttribArray(2);
// Load textures
int crateTexWidth, crateTexHeight, gridTexWidth, gridTexHeight;
unsigned char* crateImage = SOIL_load_image("crate.png", &crateTexWidth, &crateTexHeight, 0, SOIL_LOAD_RGB);
unsigned char* gridImage = SOIL_load_image("crate.png", &gridTexWidth, &gridTexHeight, 0, SOIL_LOAD_RGB);
// Generate Textures
GLuint crateTexture = {1};
glGenTextures(1, &crateTexture);
glBindTexture(GL_TEXTURE_2D, crateTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, crateTexWidth, crateTexHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, crateImage);
glGenerateMipmap(GL_TEXTURE_2D);
SOIL_free_image_data(crateImage);
glBindTexture(GL_TEXTURE_2D, 0);
// Generate Textures
GLuint gridTexture;
glGenTextures(1, &gridTexture);
glBindTexture(GL_TEXTURE_2D, gridTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, gridTexWidth, gridTexHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, gridImage);
glGenerateMipmap(GL_TEXTURE_2D);
SOIL_free_image_data(gridImage);
glBindTexture(GL_TEXTURE_2D, 0);
}
void UDestroyMesh(GLMesh& mesh)
{
glDeleteVertexArrays(1, &mesh.vao);
glDeleteBuffers(2, mesh.vbos);
}
// Implements the UCreateShaders function
bool UCreateShaderProgram(const char* vtxShaderSource, const char* fragShaderSource, GLuint& programId)
{
// Compilation and linkage error reporting
int success = 0;
char infoLog[512];
// Create a Shader program object.
programId = glCreateProgram();
// Create the vertex and fragment shader objects
GLuint vertexShaderId = glCreateShader(GL_VERTEX_SHADER);
GLuint fragmentShaderId = glCreateShader(GL_FRAGMENT_SHADER);
// Retrive the shader source
glShaderSource(vertexShaderId, 1, &vtxShaderSource, NULL);
glShaderSource(fragmentShaderId, 1, &fragShaderSource, NULL);
// Compile the vertex shader, and print compilation errors (if any)
glCompileShader(vertexShaderId); // compile the vertex shader
// check for shader compile errors
glGetShaderiv(vertexShaderId, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(vertexShaderId, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
return false;
}
glCompileShader(fragmentShaderId); // compile the fragment shader
// check for shader compile errors
glGetShaderiv(fragmentShaderId, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(fragmentShaderId, sizeof(infoLog), NULL, infoLog);
std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
return false;
}
// Attached compiled shaders to the shader program
glAttachShader(programId, vertexShaderId);
glAttachShader(programId, fragmentShaderId);
glLinkProgram(programId); // links the shader program
// check for linking errors
glGetProgramiv(programId, GL_LINK_STATUS, &success);
if (!success)
{
glGetProgramInfoLog(programId, sizeof(infoLog), NULL, infoLog);
std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
return false;
}
glUseProgram(programId); // Uses the shader program
return true;
}
void UDestroyShaderProgram(GLuint programId)
{
glDeleteProgram(programId);
}
// Define Input Callback functions
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
// Display ASCII Keycode
//cout << "ASCII: " << key << endl;
if (action == GLFW_PRESS)
keys[key] = true;
else if (action == GLFW_RELEASE)
keys[key] = false;
}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) {
/*
// Display scroll offset
if (yoffset > 0)
cout << "Scroll Up: ";
if (yoffset < 0)
cout << "Scroll Down: ";
cout << yoffset << endl;
*/
// Clamp FOV
if (fov >= 1.f && fov <= 45.f)
fov -= yoffset * 0.01f;
//Default FOV
if (fov < 1.f)
fov = 1.f;
if (fov > 45.f)
fov = 45.f;
}
void cursor_position_callback(GLFWwindow* window, double xpos, double ypos) {
// Display mouse x and y coordinates
// cout << "Mouse X: " << xpos << endl;
// cout << "Mouse Y: " << ypos << endl;
if (firstMouseMove) {
lastX = xpos;
lastY = ypos;
firstMouseMove = false;
}
// Calculate cursor offset
xChange = xpos - lastX;
yChange = lastY - ypos;
lastX = xpos;
lastY = ypos;
// Pan camera
if (isPanning) {
if (cameraPosition.z < 0.f)
cameraFront.z = 1.f;
else
cameraFront.z = -1.f;
GLfloat cameraSpeed = xChange * deltaTime;
cameraPosition += cameraSpeed * cameraRight;
cameraSpeed = yChange * deltaTime;
cameraPosition += cameraSpeed * cameraUp;
}
// Orbit camera
if (isOrbiting) {
rawYaw += xChange;
rawPitch += yChange;
// Convert Yaw and Pitch to degrees
degYaw = glm::radians(rawYaw);
// degPitch = glm::radians(rawPitch)
degPitch = glm::clamp(glm::radians(rawPitch), -glm::pi<float>() / 2.f + .1f, glm::pi<float>() / 2.f - .1f);
// Azimuth Altitude formula
cameraPosition.x = target.x + radius * cosf(degPitch) * sin(degYaw);
cameraPosition.y = target.y + radius * sinf(degPitch);
cameraPosition.z = target.z + radius * cosf(degPitch) * cosf(degYaw);
}
}
void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) {
/*
// Detect mouse button clicks
if (button == GLFW_MOUSE_BUTTON_LEFT && action == GLFW_PRESS)
cout << "LMB clicked!" << endl;
if (button == GLFW_MOUSE_BUTTON_MIDDLE && action == GLFW_PRESS)
cout << "MMB clicked!" << endl;
if (button == GLFW_MOUSE_BUTTON_RIGHT && action == GLFW_PRESS)
cout << "RMB clicked!" << endl;
*/
if (action == GLFW_PRESS)
mouseButtons[button] = true;
else if (action == GLFW_RELEASE)
mouseButtons[button] = false;
}
// Define getTarget function
glm::vec3 getTarget() {
if (isPanning)
target = cameraPosition + cameraFront;
return target;
}
// Define TransformCamera function
void TransformCamera() {
// Pan camera
if (keys[GLFW_KEY_LEFT_ALT] && mouseButtons[GLFW_MOUSE_BUTTON_MIDDLE])
isPanning = true;
else
isPanning = false;
// Orbit camera
if ((mouseButtons[GLFW_MOUSE_BUTTON_LEFT]))
isOrbiting = true;
else
isOrbiting = false;
// Reset camera
if (keys[GLFW_KEY_F])
initCamera();
}
void initCamera() {
cameraPosition = glm::vec3(0.f, 0.f, 3.f);
target = glm::vec3(0.f, 0.f, 0.f);
cameraDirection = glm::normalize(cameraPosition - target);
worldUp = glm::vec3(0.f, 1.f, 0.f);
cameraRight = glm::normalize(glm::cross(worldUp, cameraDirection));
cameraUp = glm::normalize(glm::cross(cameraDirection, cameraRight));
cameraFront = glm::normalize(glm::vec3(0.f, 0.f, -1.f));
}

Answer 1

You never actually bother to declare/define a cameraPosition (presumably) uniform in your vertex shader or set its value via an appropriate glUniform*() call.
...not that you'd really want to since then every vertex would end up being set to the same position and you'd end up with a dot somewhere (maybe) on screen.
Rather,
gl_Position = projection * view * model * vec4(cameraPosition.x, cameraPosition.y, cameraPosition.z, 1.0f);
should probably be:
gl_Position = projection * view * model * vec4(position, 1.0);
...so all your fancy geometry in verts actually has some chance of being sensibly displayed.