opengl Framebuffer offscreen to texture, colour error - c++

im trying to use a framebuffer for offscreen-render a cube. Then i try to translate it to a texture using its texture. The problem i get is when i try to put that texture on a plane. The texture colour is full based on one primary colour: Reed, Green or Blue. I dont know where is the problem, maybe a cast problem from float to double? I really dont know what to think or where to explore.
Here is a gif of what i get. In this gif you can see the normal cube without offscreen render. The second GREEN cube is the framebuffer's texture printed on a plane:
here is the code I use. Its based on Qt but there is no difference from this to glut. I explain it to make easier to understand:
initializeGL: I declare the framebuffer and its attachments
PaintGL: draws the cube without using the FB if i dont "left click" to enable this (first part of the gif, it works perfect). If i left click, then the routine changes and paint the cube on the FrameBuffer, and then i paint its texture on a plane. (second part of the gif, it paints my texture GREEN)
setProyection: set the glOrtho for the normal cube draw.
#include "WidgetOpenGL.h"
WidgetOpenGL::WidgetOpenGL(QWidget *parent) : QOpenGLWidget(parent)
{
}
void WidgetOpenGL::initializeGL()
{
desplazamientoX = 1;
desplazamientoY = 0;
initializeOpenGLFunctions();
glClearColor(0.0, 0.0, 0.0, 0.0);
glEnable(GL_DEPTH_TEST);
buttonpressed = false;
glGenFramebuffers(1, &buffer);
glBindFramebuffer(GL_FRAMEBUFFER, buffer);
glGenTextures(1, &renderedTexture);
glBindTexture(GL_TEXTURE_2D, renderedTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1024, 768, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glGenRenderbuffers(1, &renderedDepth);
glBindRenderbuffer(GL_RENDERBUFFER, renderedDepth);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, 1024, 768);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, renderedDepth);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, renderedTexture, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
setProyection();
setModelView();
}
void WidgetOpenGL::paintGL()
{
if (buttonpressed)
{
glBindFramebuffer(GL_FRAMEBUFFER, buffer);
glViewport(0, 0, 1024, 768);
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
setProyection();
setModelView();
glTranslatef(0.0, 0.0, -2.0);
setRotation();
glBegin(GL_QUADS);
// top
glColor3f(1.0f, 0.0f, 0.0f);
glNormal3f(0.0f, 1.0f, 0.0f);
glVertex3f(-0.5f, 0.5f, 0.5f);
glVertex3f(0.5f, 0.5f, 0.5f);
glVertex3f(0.5f, 0.5f, -0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glEnd();
glBegin(GL_QUADS);
// front
glColor3f(0.0f, 1.0f, 0.0f);
glNormal3f(0.0f, 0.0f, 1.0f);
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f(0.5f, -0.5f, 0.5f);
glVertex3f(0.5f, 0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, 0.5f);
glEnd();
glBegin(GL_QUADS);
// right
glColor3f(0.0f, 0.0f, 1.0f);
glNormal3f(1.0f, 0.0f, 0.0f);
glVertex3f(0.5f, -0.5f, 0.5f);
glVertex3f(0.5f, -0.5f, -0.5f);
glVertex3f(0.5f, 0.5f, -0.5f);
glVertex3f(0.5f, 0.5f, 0.5f);
glEnd();
glBegin(GL_QUADS);
// left
glColor3f(0.0f, 0.0f, 0.5f);
glNormal3f(-1.0f, 0.0f, 0.0f);
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glVertex3f(-0.5f, -0.5f, -0.5f);
glEnd();
glBegin(GL_QUADS);
// bottom
glColor3f(0.5f, 0.0f, 0.0f);
glNormal3f(0.0f, -1.0f, 0.0f);
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f(0.5f, -0.5f, 0.5f);
glVertex3f(0.5f, -0.5f, -0.5f);
glVertex3f(-0.5f, -0.5f, -0.5f);
glEnd();
glBegin(GL_QUADS);
// back
glColor3f(0.0f, 0.5f, 0.0f);
glNormal3f(0.0f, 0.0f, -1.0f);
glVertex3f(0.5f, 0.5f, -0.5f);
glVertex3f(0.5f, -0.5f, -0.5f);
glVertex3f(-0.5f, -0.5f, -0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glEnd();
glFlush();
if (buttonpressed)
{
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// QImage img = frameBuffer->toImage();
// img.save("Hola.jpg");
//draw plane with texture
setViewport();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-2.0, 2.0, -2.0, 2.0, -2.0, 2.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, renderedTexture);
glBegin(GL_QUADS);
glTexCoord2d(0.0f, 0.0f);
glVertex3f(-1.0, -1.0, -1.0);
glTexCoord2d(1.0f, 0.0f);
glVertex3f(1.0, -1.0, -1);
glTexCoord2d(1.0f, 1.0f);
glVertex3f(1.0, 1.0, -1.0);
glTexCoord2d(0.0f, 1.0f);
glVertex3f(-1.0, 1.0, -1.0);
glEnd();
glBindTexture(GL_TEXTURE_2D, 0);
glDisable(GL_TEXTURE_2D);
glFlush();
}
}
void WidgetOpenGL::resizeGL(int w, int h)
{
setViewport();
setProyection();
setModelView();
}
void WidgetOpenGL::setViewport()
{
int ancho = this->width();
int alto = this->height();
glViewport(0, 0, ancho, alto);
}
void WidgetOpenGL::setProyection()
{
int ancho = this->width();
int alto = this->height();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 10.0);
//gluPerspective(90.0f, ancho / (GLdouble)alto, 0.0f, 10.0f);
}
void WidgetOpenGL::setModelView()
{
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void WidgetOpenGL::mouseMoveEvent(QMouseEvent *event)
{
desplazamientoY += ((event->x() - initX) * 360) / (GLdouble)width();
desplazamientoX += ((event->y() - initY) * 360) / (GLdouble)height();
initX = event->x();
initY = event->y();
if (((int)desplazamientoX % 360) == 0) desplazamientoX = 0;
if (((int)desplazamientoY % 360) == 0) desplazamientoY = 0;
repaint();
}
void WidgetOpenGL::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
{
initX = event->x();
initY = event->y();
}
else
{
buttonpressed = !buttonpressed;
repaint();
}
}
void WidgetOpenGL::setRotation()
{
glRotatef(desplazamientoX, 1.0, 0.0, 0.0);
glRotatef(desplazamientoY, 0.0, 1.0, 0.0);
}
and here is the header file if needed:
#ifndef WIDGETOPENGL_H
#define WIDGETOPENGL_H
#include <QtWidgets/QMainWindow>
#include <QtWidgets/qopenglwidget.h>
#include <QtOpenGL>
#include <GL/GLU.h>
class WidgetOpenGL : public QOpenGLWidget, protected QOpenGLFunctions
{
Q_OBJECT
public:
WidgetOpenGL(QWidget *parent);
signals:
void screenClicked();
protected:
void initializeGL();
void paintGL();
void resizeGL(int w, int h);
void setViewport();
void setProyection();
void setModelView();
private:
int initX;
int initY;
QOpenGLFramebufferObject *frameBuffer;
GLuint buffer;
GLuint renderedTexture;
GLuint renderedDepth;
bool buttonpressed;
QImage image;
GLdouble desplazamientoX;
GLdouble desplazamientoY;
void setRotation();
void mouseMoveEvent(QMouseEvent *event);
void mousePressEvent(QMouseEvent *event);
};
#endif

Solved! the problem were that i was painting the texture on a green plane. Thats because the last glcolor3f is green (used when i paint the back plane of the real cube).
I only have to add glColor3f(1.0,1.0,1.0) before drawing the plane, to make a white plane.

Related

I'm having a problem with movement in opengl 3D

I'm having a problem in OpenGL, when I press W, A, S, D everything works normal, but when I press space or shift it happens:
The cube disappears before the end of the screen. Depending on the value of xrot and yrot another axis gets this problem.
I'm a beginner in openGL 3D and I don't know why that happens.
code:
float xrot = 100.0f;
float yrot = -100.0f;
float tra_x = 0.0f;
float tra_y = 0.0f;
float tra_z = 0.0f;
GLFWwindow* window;
void drawBox()
{
glEnable(GL_TEXTURE_2D);
glBegin(GL_QUADS);
glEnable(3553);
glBegin(GL_QUADS);
glColor3f(1.0f, 0.0f, 0.0f);
// FRONT
glVertex3f(-0.5f, -0.5f, 0.5f);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex3f(0.5f, -0.5f, 0.5f);
glVertex3f(0.5f, 0.5f, 0.5f);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex3f(-0.5f, 0.5f, 0.5f);
// BACK
glVertex3f(-0.5f, -0.5f, -0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex3f(0.5f, 0.5f, -0.5f);
glVertex3f(0.5f, -0.5f, -0.5f);
glColor3f(0.0f, 1.0f, 0.0f);
// LEFT
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, 0.5f);
glColor3f(0.0f, 0.0f, 1.0f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex3f(-0.5f, -0.5f, -0.5f);
// RIGHT
glVertex3f(0.5f, -0.5f, -0.5f);
glVertex3f(0.5f, 0.5f, -0.5f);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex3f(0.5f, 0.5f, 0.5f);
glColor3f(0.0f, 0.0f, 1.0f);
glVertex3f(0.5f, -0.5f, 0.5f);
glColor3f(0.0f, 0.0f, 1.0f);
// TOP
glVertex3f(-0.5f, 0.5f, 0.5f);
glVertex3f(0.5f, 0.5f, 0.5f);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex3f(0.5f, 0.5f, -0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glColor3f(1.0f, 0.0f, 0.0f);
// BOTTOM
glVertex3f(-0.5f, -0.5f, 0.5f);
glColor3f(0.0f, 0.0f, 1.0f);
glVertex3f(-0.5f, -0.5f, -0.5f);
glVertex3f(0.5f, -0.5f, -0.5f);
glVertex3f(0.5f, -0.5f, 0.5f);
glEnd();
}
void display(void)
{
glDisable(GL_BLEND);
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClearDepth(1.0);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glRotatef(yrot, -1.0f, 0.0f, 0.0f);
glRotatef(xrot, 0.0f, 1.0f, 0.0f);
glTranslatef(-tra_x, tra_y, -tra_z);
drawBox();
glFlush();
glfwSwapBuffers(window);
}
void framebuffer_resize_callback(GLFWwindow* window, int fbW, int fbH)
{
glViewport(0, 0, fbW, fbH);
}
int main(void)
{
if (!glfwInit())
return -1;
glfwWindowHint(GLFW_SAMPLES, 2);
window = glfwCreateWindow(640, 480, "Test", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
glfwSetFramebufferSizeCallback(window, framebuffer_resize_callback);
glfwMakeContextCurrent(window);
glClearColor(0.93f, 0.93f, 0.93f, 0.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glClearDepth(1.0f);
while (!glfwWindowShouldClose(window))
{
display();
if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS) {
tra_x += 0.1f;
}
if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS) {
tra_x -= 0.1f;
}
if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) {
tra_z -= 0.1f;
}
if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) {
tra_z += 0.1f;
}
if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS) {
tra_y += 0.1f;
}
if (glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS) {
tra_y -= 0.1f;
}
glfwPollEvents();
}
}
The object is clipped by the fare plane of the Orthographic projection. The projection matrix defines the volume (clip space) which is projected on to 2 dimensional viewport. Actually you don't set a projection matrix, thus the projection is the Identity matrix. Hence, view space, clip space and normalized device space are the same and the viewing volume is a unique cube, with the left, bottom, near of (-1, -1, -1) and the right, top, far of (1, 1, 1). Hence the near plane is at -1 and the far plane is at 1. All the geometry which is out of this space is clipped.
Use glOrtho to define a clip space with a larger scale. For instance:
void display(void)
{
// [...]
# set projection matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1, 1, -1, -1, -10, 10); // near = -10, far = 10
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// [...]
Alternatively you can use Perspective projection. At perspective projection the viewing volume is a [Frustum](https://en.wikipedia.org/wiki/Viewing_frustum. Hence you have to shift the object along the negative z axis in between the near and far plane.
Create a perspective projection by gluPerspective and move the object in between then near and far plane by gluLookAt:
void display(void)
{
// [...]
# set projection matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//glOrtho(-1, 1, -1, -1, -10, 10); // near = -10, far = 10
gluPerspective(90.0, 480.0/640.0, 0.1, 20.0)
// set view matrix
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0, 0, 5.0, 0, 0, 0, 0, 1.0, 0);
// [...]
What exactly are eye space coordinates?

glColor3f not working on gluSphere

I am currently rendering a solar system of planets in my 3d space but every single planet is black even when light hits the sphere. The spheres are rendered last in my render function. Had the colors working when the spheres were being rendered on their own but now i've added my sky box and other quads all the spheres refuse to be colored.
#include "Scene.h"
float rotation;
float rotation2;
int direction;
int speed;
Scene::Scene(Input *in)
{
// Initialise variables
rotation = 20;
rotation2 = 0;
direction = 1;
speed = 5;
myTexture = 0;
skyBox = 0;
// Store pointer for input class
input = in;
// OpenGL settings
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.39f, 0.58f, 93.0f, 1.0f); // Cornflour Blue Background
glClearDepth(1.0f); // Depth Buffer Setup
glClearStencil(0); // Clear stencil buffer
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glEnable(GL_LIGHTING); // Enables Lighting
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
// Other OpenGL / render setting should be applied here.
myTexture = SOIL_load_OGL_texture
(
"gfx/neongrid.png",
SOIL_LOAD_AUTO,
SOIL_CREATE_NEW_ID,
SOIL_FLAG_MIPMAPS | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT
);
skyBox = SOIL_load_OGL_texture
(
"gfx/starField.png",
SOIL_LOAD_AUTO,
SOIL_CREATE_NEW_ID,
SOIL_FLAG_MIPMAPS | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT
);
glEnable(GL_TEXTURE_2D);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
camera = new Camera();
}
void Scene::update(float dt)
{
// Update camera position
camera->update(input, dt);
// Handle user input
if (input->isKeyDown(43))
{
direction = 1;
input->SetKeyUp(43);
}
else if (input->isKeyDown(45))
{
direction = -1;
input->SetKeyUp(45);
}
// Update scene related variables
rotation += speed * dt;
rotation2 += (speed *2) * dt;
if (input->isKeyDown('p') && WF == false)
{
WF = true;
input->SetKeyUp('p');
glPolygonMode(GL_FRONT, GL_LINE);
}
if (input->isKeyDown('p') && WF == true)
{
WF = false;
input->SetKeyUp('p');
glPolygonMode(GL_FRONT, GL_FILL);
}
// Calculate FPS for output
calculateFPS();
}
void Scene::render() {
// Clear Color and Depth Buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Reset transformations
glLoadIdentity();
// Set the camera
gluLookAt(camera->getPosition().x, camera->getPosition().y, camera->getPosition().z,
camera->getLookAt().x, camera->getLookAt().y, camera->getLookAt().z,
camera->getUp().x, camera->getUp().y, camera->getUp().z);
glutWarpPointer(400, 300);
glutSetCursor(GLUT_CURSOR_FULL_CROSSHAIR);
// Lighting
GLfloat Light_Ambient[] = { 0.2f, 0.2f, 0.2f, 1.0f };
GLfloat Light_Diffuse[] = { 9.0f, 9.0f, 9.0f, 1.0f };
GLfloat Light_Position[] = { 2.0f, 2.0f, 2.0f, 1.0f };
glLightfv(GL_LIGHT0, GL_AMBIENT, Light_Ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, Light_Diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, Light_Position);
glEnable(GL_LIGHT0);
glDisable(GL_DEPTH_TEST);
#pragma region skybox
glPushMatrix();
glTranslatef(camera->getPosition().x, camera->getPosition().y, camera->getPosition().z);
glBindTexture(GL_TEXTURE_2D, skyBox);
glBegin(GL_QUADS);
//Back
glNormal3f(0.0f, 0.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glNormal3f(0.0f, 0.0f, 1.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
glNormal3f(0.0f, 0.0f, 1.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
glNormal3f(0.0f, 0.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
//Right
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, -1.0f);
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
//front
glNormal3f(0.0f, 0.0f, -1.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
glNormal3f(0.0f, 0.0f, -1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glNormal3f(0.0f, 0.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glNormal3f(0.0f, 0.0f, -1.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, -1.0f);
//left
glNormal3f(-1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glNormal3f(-1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glNormal3f(-1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glNormal3f(-1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
//top
glNormal3f(0.0f, 1.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glNormal3f(0.0f, 1.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
glNormal3f(0.0f, 1.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, -1.0f);
glNormal3f(0.0f, 1.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
//bottom
glNormal3f(0.0f, -1.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glNormal3f(0.0f, -1.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
glNormal3f(0.0f, -1.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
glNormal3f(0.0f, -1.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glEnd();
#pragma endregion
glEnable(GL_DEPTH_TEST);
glPopMatrix();
glPushMatrix();
#pragma region wall
glBindTexture(GL_TEXTURE_2D, myTexture);
glTranslatef(0.0, 0.0, 0.0);
glScalef(5.0f, 5.0f, 5.0f);
glBegin(GL_QUADS);
// first face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(0.0f, 1.0f, 0.0f);
// second face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, 0.0f);
// third face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 0.0f, 0.0f);
// fourth face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(0.0f, 0.0f, 0.0f);
glEnd();
glPopMatrix();
glPushMatrix();
glBindTexture(GL_TEXTURE_2D, myTexture);
glScalef(5.0f, 5.0f, 5.0f);
glBegin(GL_QUADS);
// first face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(0.0f, 0.0f, 0.0f);
// second face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 0.0f, 0.0f);
// third face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 0.0f, -1.0f);
// fourth face
glNormal3f(1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(0.0f, 0.0f, -1.0f);
glEnd();
#pragma endregion
glPopMatrix();
glPushMatrix();
// Render sun
glEnable(GL_TEXTURE_2D);
glColor3f(1.0f, 1.0f, 1.0f);
glBindTexture(GL_TEXTURE_2D, NULL);
glTranslatef(0.5, 0.5, -0.5);
glColor3f(1.0f, 0.0f, 0.0f);
gluSphere(gluNewQuadric(), 0.20, 20, 20);
glPushMatrix(); // Push for default matrix
// Render Planet 1
glRotatef(rotation, 0.5, 0.5, 0);
glTranslatef(0, 0, 1);
glScalef(1, 1, 1);
glColor3f(0.0f, 2.0f, 0.0f);
gluSphere(gluNewQuadric(), 0.20, 10, 10);
glPopMatrix(); // Pop off stack back to sun matrix
glPushMatrix(); // Push for default matrix
// Render Planet 2
glRotatef(rotation2, 0, 1, 0);
glTranslatef(2, 0, 0);
glScalef(0.5, 0.5, 0.5);
glColor3f(0.0f, 0.0f, 1.0f);
gluSphere(gluNewQuadric(), 0.20, 5, 5);
glPushMatrix(); // Pop back to sun
// Render a moon around Planet 2
glRotatef((rotation*2.0), 0, 1, 0);
glTranslatef(1.5, 0, 0);
glScalef(0.3, 0.3, 0.3);
glColor3f(0.0f, 0.0f, 1.0f);
gluSphere(gluNewQuadric(), 0.20, 20, 20);
glPopMatrix(); // Pop to planet 2
glPushMatrix(); // Push for default matrix
// Render a SECOND moon around Planet 2
glRotatef((rotation * 2), 0, 0, 1);
glTranslatef(1.5, 0, 0);
glScalef(0.3, 0.3, 0.3);
glColor3f(0.0f, 0.0f, 1.0f);
gluSphere(gluNewQuadric(), 0.20, 20, 20);
glPopMatrix();
//glPopMatrix();
glPopMatrix(); // Go back to sun!
glPushMatrix();
glTranslatef(2, 2, 2);
glColor3f(1, 0, 0);
gluSphere(gluNewQuadric(), 0.5, 20, 20);
glPopMatrix();
// End render geometry --------------------------------------
// Render text, should be last object rendered.
renderTextOutput();
// Swap buffers, after all objects are rendered.
glutSwapBuffers();
}
// Handles the resize of the window. If the window changes size the perspective matrix requires re-calculation to match new window size.
void Scene::resize(int w, int h)
{
width = w;
height = h;
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if (h == 0)
h = 1;
float ratio = (float)w / (float)h;
fov = 45.0f;
nearPlane = 0.1f;
farPlane = 100.0f;
// Use the Projection Matrix
glMatrixMode(GL_PROJECTION);
// Reset Matrix
glLoadIdentity();
// Set the viewport to be the entire window
glViewport(0, 0, w, h);
// Set the correct perspective.
gluPerspective(fov, ratio, nearPlane, farPlane);
// Get Back to the Modelview
glMatrixMode(GL_MODELVIEW);
}
// Calculates FPS
void Scene::calculateFPS()
{
frame++;
time = glutGet(GLUT_ELAPSED_TIME);
if (time - timebase > 1000) {
sprintf_s(fps, "FPS: %4.2f", frame*1000.0 / (time - timebase));
timebase = time;
frame = 0;
}
}
// Compiles standard output text including FPS and current mouse position.
void Scene::renderTextOutput()
{
// Render current mouse position and frames per second.
sprintf_s(mouseText, "Mouse: %i, %i", input->getMouseX(), input->getMouseY());
displayText(-1.f, 0.96f, 1.f, 0.f, 0.f, mouseText);
displayText(-1.f, 0.90f, 1.f, 0.f, 0.f, fps);
}
// Renders text to screen. Must be called last in render function (before swap buffers)
void Scene::displayText(float x, float y, float r, float g, float b, char* string) {
// Get Lenth of string
int j = strlen(string);
// Swap to 2D rendering
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, 5, 100);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Orthographic lookAt (along the z-axis).
gluLookAt(0.0f, 0.0f, 10.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);
// Set text colour and position.
glColor3f(r, g, b);
glRasterPos2f(x, y);
// Render text.
for (int i = 0; i < j; i++) {
glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, string[i]);
}
// Reset colour to white.
glColor3f(1.f, 1.f, 1.f);
// Swap back to 3D rendering.
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(fov, ((float)width/(float)height), nearPlane, farPlane);
glMatrixMode(GL_MODELVIEW);
}
Updated sun code :
// Render sun
glTranslatef(0.5, 0.5, -0.5);
glColor3f(1.0f, 0.0f, 0.0f);
gluSphere(gluNewQuadric(), 0.20, 20, 20);
glPushMatrix(); // Push for default matrix
// Render Planet 1
glRotatef(rotation, 0.5, 0.5, 0);
glTranslatef(0, 0, 1);
glScalef(1, 1, 1);
glColor3f(0.0f, 2.0f, 0.0f);
gluSphere(gluNewQuadric(), 0.20, 10, 10);
glPopMatrix(); // Pop off stack back to sun matrix
glPushMatrix(); // Push for default matrix
Found out i was missing a OpenGL setting
glEnable(GL_COLOR_MATERIAL);
Inserted at the start of Scene
Try to end glEnable(GL_TEXTURE_2D); with glDisable(GL_TEXTURE_2D); after you render sun.
If problem appeared after you added skybox. Check if vertices are in right order.

Orbiting sphere should cast spot light on central cube

I'm writing a program that draws a rotating cube (with texture) in the middle of the screen followed by a small yellow sphere that orbits around the cube. The idea is to make the sphere as a spot light source that illuminates the cube.
Here is the problem: as you can see in the images below, I'm failing to achieve the spot light effect. It seems that the entire cube gets lighted:
I'm setting GL_SPOT_DIRECTION to be the cube position. I didn't set surface normals because I'm struggling to understand how to compute them for the cube, and I'm not sure a simple graphic application like this really requires it.
I'm sharing the code below:
main.cpp:
#include <QApplication>
#include "glwidget.h"
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
GLWidget gl_widget;
gl_widget.show();
return app.exec();
}
GLWidget.h:
#pragma once
#include <QGLWidget>
#include <QImage>
class GLWidget : public QGLWidget
{
Q_OBJECT
public:
explicit GLWidget(QWidget* parent = 0);
virtual ~GLWidget();
void _draw_texture_cube(int w, int h);
void _draw_light();
/* OpenGL initialization, viewport resizing, and painting */
void initializeGL();
void paintGL();
void resizeGL( int width, int height);
/* enable the user to interact directly with the scene using the keyboard */
void keyPressEvent(QKeyEvent *e);
private:
int _width;
int _height;
QImage* _img;
GLuint _texture;
float xrot;
float yrot;
float zrot;
bool _light_on;
bool _must_rotate;
bool _pause_light;
GLfloat _light_pos[3];
GLfloat _cube_pos[3];
GLUquadricObj* _quadratic;
protected slots:
void _tick();
};
GLWidget.cpp:
#include "GLWidget.h"
#include <iostream>
#include <QKeyEvent>
#include <QTimer>
#include <cmath>
#define LIGHT_MOVEMENT_SPEED 20.0f // Degrees per second
#define pi 3.141592654f
GLWidget::GLWidget(QWidget *parent)
: QGLWidget(parent), _img(NULL), _light_on(true), _must_rotate(true),
_pause_light(false), _quadratic(NULL)
{
_width = 0;
_height = 0;
_texture = 0;
xrot = 0.f;
yrot = 0.f;
zrot = 0.f;
// Set central cube position
_cube_pos[0] = 0.0f;
_cube_pos[1] = 0.0f;
_cube_pos[2] = -7.0f;
// Set light position
_light_pos[0] = 0.5f;
_light_pos[1] = 0.5f;
_light_pos[2] = -7.0f;
}
GLWidget::~GLWidget()
{
if (_img)
delete _img;
glDeleteTextures(1, &_texture);
}
void GLWidget::_tick()
{
update(); // triggers paintGL()
QTimer::singleShot(33, this, SLOT(_tick()));
}
void GLWidget::initializeGL()
{
std::cout << "GLWidget::initializeGL" << std::endl;
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Black Background
glEnable(GL_CULL_FACE);
/* Load bitmap */
glEnable(GL_TEXTURE_RECTANGLE_ARB);
glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
if (!_img)
{
std::cout << "GLWidget::paintGL: loading image" << std::endl;
QImage tmp(":/crate.jpg");
if (tmp.isNull())
{
std::cout << "GLWidget::paintGL: !!! Failed QImage #1" << std::endl;
return;
}
_img = new QImage(QGLWidget::convertToGLFormat(tmp));
}
/* Convert bitmap into texture */
// Create The Texture
glGenTextures(1, &_texture);
// Typical Texture Generation Using Data From The Bitmap
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _texture);
// Generate The Texture
glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0,
GL_RGBA, _img->width(), _img->height(), 0,
GL_RGBA, GL_UNSIGNED_BYTE, _img->bits());
if (glGetError() != GL_NO_ERROR)
{
std::cout << "GLWidget::paintGL: !!! Failed glTexImage2D" << std::endl;
return;
}
/* Setup lighting */
glShadeModel(GL_SMOOTH); //Smooth color shading
// Light properties
GLfloat AmbientLight[4] = {0.2, 0.2, 0.2, 1.0};
GLfloat DiffuseLight[4] = {0.8, 0.8, 0.8, 1.0}; // color
GLfloat SpecularLight[4] = {1.0, 1.0, 1.0, 1.0}; // bright
GLfloat SpecRef[] = {0.7f, 0.7f, 0.7f, 1.0f};
GLubyte Shine = 60.0;
//glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, AmbientLight);
glLightfv(GL_LIGHT0, GL_AMBIENT, AmbientLight);
glLightfv(GL_LIGHT0, GL_DIFFUSE, DiffuseLight);
glLightfv(GL_LIGHT0, GL_SPECULAR, SpecularLight);
glLightfv(GL_LIGHT0, GL_POSITION, _light_pos);
glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
glMaterialfv(GL_FRONT, GL_SPECULAR, SpecRef); // refletância do material
glMaterialf(GL_FRONT, GL_SHININESS, Shine); // concentração do brilho
glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, 0);
//glColorMaterial(GL_FRONT,GL_DIFFUSE);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_DEPTH_TEST);
// Sphere
_quadratic = gluNewQuadric(); // Create A Pointer To The Quadric Object
gluQuadricNormals(_quadratic, GLU_SMOOTH); // Create Smooth Normals
gluQuadricTexture(_quadratic, GL_TRUE); // Create Texture Coords
/* Start the timer */
_tick();
}
/* Draw the central cube with texture
*/
void GLWidget::_draw_texture_cube(int w, int h)
{
glPushMatrix();
glTranslatef(_cube_pos[0], _cube_pos[1], _cube_pos[2]);
glRotatef ( xrot, 1.0, 0.0, 0.0 );
glRotatef ( yrot, 0.0, 1.0, 0.0 );
glRotatef ( zrot, 0.0, 0.0, 1.0 );
glColor3f(1.0f, 1.0f, 1.0f);
glBegin(GL_QUADS); // Draw A Cube
// Front Face
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
glTexCoord2f(w, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
glTexCoord2f(w, h); glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, h); glVertex3f(-1.0f, 1.0f, 1.0f);
// Back Face
glTexCoord2f(w, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
glTexCoord2f(w, h); glVertex3f(-1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, h); glVertex3f( 1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
// Top Face
glTexCoord2f(0.0f, h); glVertex3f(-1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 1.0f);
glTexCoord2f(w, 0.0f); glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(w, h); glVertex3f( 1.0f, 1.0f, -1.0f);
// Bottom Face
glTexCoord2f(w, h); glVertex3f(-1.0f, -1.0f, -1.0f);
glTexCoord2f(0.0f, h); glVertex3f( 1.0f, -1.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
glTexCoord2f(w, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
// Right face
glTexCoord2f(w, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
glTexCoord2f(w, h); glVertex3f( 1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, _img->height()); glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
// Left Face
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
glTexCoord2f(w, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
glTexCoord2f(w, h); glVertex3f(-1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, h); glVertex3f(-1.0f, 1.0f, -1.0f);
glEnd();
glPopMatrix();
if (_must_rotate)
{
xrot += 0.6f;
yrot += 0.4f;
zrot += 0.8f;
}
}
/* Draw light source and light model (sphere)
*/
void GLWidget::_draw_light()
{
if (_light_on)
{
glEnable(GL_LIGHT0); // enable lights that we use
}
else
{
glDisable(GL_LIGHT0);
}
static float light_angle = 25.0f;
if (!_pause_light) // stop moving the light source
{
light_angle += LIGHT_MOVEMENT_SPEED * 0.1;
if (light_angle > 360.0f)
light_angle -= 360.0f;
}
/* Set light source position */
_light_pos[0] = 4.0f * (float) cos(light_angle * pi / 180.0f);
_light_pos[1] = 4.0f * (float) sin(light_angle * pi / 180.0f);
_light_pos[2] = -7;
glLightfv(GL_LIGHT0, GL_POSITION, _light_pos);
GLfloat SpotDir[] = {_cube_pos[0], _cube_pos[1], _cube_pos[2], 0.0 };
glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, SpotDir);
glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 150.0);
glLightf(GL_LIGHT0, GL_SPOT_EXPONENT, 15.0);
/* Set the light model position to be the same as the light source */
glPushMatrix();
glTranslatef(_light_pos[0], _light_pos[1], _light_pos[2]);
glColor3ub(255, 255, 0); // yellow
gluSphere(_quadratic, 0.2f, 32, 32); // draw sphere
glPopMatrix();
}
void GLWidget::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glMatrixMode ( GL_MODELVIEW ); // Select The Model View Matrix
glLoadIdentity(); // Reset The Current Modelview Matrix
/* Draw central cube */
glEnable(GL_TEXTURE_RECTANGLE_ARB);
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _texture); // Select Our Texture
_draw_texture_cube(_img->width(), _img->height());
glDisable(GL_TEXTURE_RECTANGLE_ARB);
/* Draw light source and light model*/
_draw_light();
}
void GLWidget::resizeGL( int w, int h)
{
_width = w;
_height = h;
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix
if (h == 0) // Calculate The Aspect Ratio Of The Window
gluPerspective ( 60, ( float ) w, 0.4, 500.0 );
else
gluPerspective ( 60, ( float ) w / ( float ) h, 0.4, 500.0 );
glMatrixMode ( GL_MODELVIEW ); // Select The Model View Matrix
glLoadIdentity ( ); // Reset The Model View Matrix
gluLookAt(0.0, 0.0, 2.0, // eye
0.0, 0.0, 0.0, // center
0.0, 1.0, 0.0); // up
}
void GLWidget::keyPressEvent(QKeyEvent *e)
{
switch (e->key())
{
case Qt::Key_L:
if (_light_on)
_light_on = false;
else
_light_on = true;
break;
case Qt::Key_P:
if (_pause_light)
_pause_light = false;
else
_pause_light = true;
break;
case Qt::Key_R:
if (_must_rotate)
_must_rotate = false;
else
_must_rotate = true;
break;
default:
break;
}
}
Lighting.pro:
QT += core gui opengl
SOURCES += \
GLWidget.cpp \
main.cpp
HEADERS += \
GLWidget.h
RESOURCES += \
resource.qrc
What needs to be changed in this application in order to achieve the desired effect?
You do not specify any normals for your cube faces. As OpenGL is a state machine, it will use the default surface normal for all vertices, hence all of your faces. As the normal vector is crucial for the lighting, all of your faces will be lit almost identical (vertex postions still are different, but the effect is weak).
You should also be aware that the fixed function lighting of OpenGL is done per vertex. If you really want to see a good spotlight on the cuve, you would either need to tessalate it so more vertices are used where the lighting equation is actually evaluated, or use shaders for per-fragment lighting.

OpenGL picking shows nothing after the pick

So I have 2 cubes in a display list and I want one of them be pickable so I can maybe change his color or something like that.
When I click on a cube then the screen turns black and nothing happens, the console gives me output of the closest hit but the screen turns black and doesn't show anything.
Here is my cpp file:
#include "glwidget.h"
#include <QDomDocument>
#include <QDebug>
#include <QFile>
#include <math.h>
#include <QString>
#include <stdlib.h>
GLWidget::GLWidget(QWidget *parent):QGLWidget(parent)
{
camPosx = 0.0, camPosy = 0.0, camPosz = 1.0;
camViewx = 0.0, camViewy = 0.0, camViewz = 0.0;
camUpx = 0.0, camUpy = 1.0, camUpz = 0.0;
camAngle = 0.0;
camViewz = -cos(camAngle);
camViewx = sin(camAngle);
mode = 1;
timer = new QTimer();
connect( timer, SIGNAL(timeout()), this, SLOT(updateGL()) );
}
void GLWidget::initializeGL() {
loadGLTextures();
glEnable(GL_TEXTURE_2D); // Enable Texture Mapping
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glEnable(GL_LIGHT0); // Quick And Dirty Lighting (Assumes Light0 Is Set Up)
glEnable(GL_LIGHTING); // Enable Lighting
glEnable(GL_COLOR_MATERIAL); // Enable Material Coloring
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Perspective Calculations
buildLists(2); // Creating displaylist #
glLoadIdentity();
timer->start(50);
}
void GLWidget::resizeGL(int width, int height) {
//set viewport
glViewport(0,0,width,height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//set persepective
//change the next line order to have a different perspective
aspect_ratio=(GLdouble)width/(GLdouble)height;
gluPerspective(45.0f, aspect_ratio, 0.1 , 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void GLWidget::paintGL() {
glEnable(GL_DEPTH_TEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
// store current matrix
glMatrixMode( GL_MODELVIEW );
glPushMatrix( );
gluLookAt(camPosx ,camPosy ,camPosz,
camPosx + camViewx,camViewy,camPosz + camViewz,
camUpx, camUpy, camUpz );
if (mode == 2) {
startPicking();
}
glColor3f(1.0f,0.0f,0.0f);
glCallList(displayList[0]);
glTranslatef(5.0,0.0,0.0);
glColor3f(0.0f,1.0f,1.0f);
glCallList(displayList[0]);
if (mode == 2)
stopPicking();
// glEnable( GL_LIGHTING );
// glEnable( GL_LIGHT0 );
// glScalef(10.0,10.0,10.0);
// glBindTexture(GL_TEXTURE_2D, texture[0]);
// glBegin(GL_QUADS);
// // Front Face
// glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
// glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
// glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
// glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
// // Back Face
// glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
// glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
// glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
// glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
// // Top Face
// glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
// glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Texture and Quad
// glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Bottom Right Of The Texture and Quad
// glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
// // Bottom Face
// glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f); // Top Right Of The Texture and Quad
// glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Top Left Of The Texture and Quad
// glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
// glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
// // Right face
// glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
// glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
// glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
// glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
// // Left Face
// glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
// glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
// glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
// glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
// glEnd();
// // XML
// QDomDocument doc( "AdBookML" );
// QDomNode n;
// QDomElement e;
// QFile file( "test2.xml" );
// QString s;
// QStringList sl;
//// if( !file.open(QIODevice::ReadOnly))
//// qDebug("probleem bij het openen");
// if( !doc.setContent( &file ) )
// {
// file.close();
// }
// file.close();
// QDomElement root = doc.documentElement();
// if( root.tagName() != "playlist" )
// // qDebug("root is different");
// //qDebug( root.tagName() );
// // doorheen u boom lopen
// n = root;
// float f1, f2, f3;
// glDisable( GL_LIGHTING );
// glBegin(GL_TRIANGLES);
// for(int i = 0; i< n.childNodes().length(); i++) // voor alle triangles
// {
// if(n.childNodes().at(i).toElement().tagName() == "triangle")
// {
// for(int j =0; j < 4; j++) // voor alle punten
// {
// e = n.childNodes().at(i).childNodes().at(j).toElement(); // e is een punt
// //qDebug(e.tagName());
// s = e.text();
// sl = s.split(" "); // opsplitsen naar het x, y , z coordinaat;
// f1 = sl.at(0).toFloat();
// f2 = sl.at(1).toFloat();
// f3 = sl.at(2).toFloat();
// if( j > 0)
// glVertex3f(f1, f2, f3); // de vertex tekenen
// if(j == 0)
// glColor3f(f1,f2,f3);
// }
// }
// }
// glEnd();
// glEnable(GL_LIGHTING);
// restore current matrix
glMatrixMode( GL_MODELVIEW );
glPopMatrix( );
}
void GLWidget::loadGLTextures()
{
QImage t;
QImage b;
if ( !b.load( "images/redbrick.png" ) )
{
qDebug("Didn't found the image.");
b = QImage( 16, 16, QImage::Format_RGB32 );
b.fill( 1 );
}
t = QGLWidget::convertToGLFormat( b );
glGenTextures( 1, &texture[0] );
glBindTexture( GL_TEXTURE_2D, texture[0] );
glTexImage2D( GL_TEXTURE_2D, 0, 3, t.width(), t.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, t.bits() );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
}
//Functie die display lists kan aanmaken, het aantal ( is het aantal displaylists )
GLvoid GLWidget::buildLists(int aantal)
{
displayList = new GLuint[aantal];
for(int i = 0; i < aantal; i++)
{
displayList[i]=glGenLists(aantal); // Maak x Aantal displaylists
glNewList(displayList[i],GL_COMPILE); //start met de eerste display list te compile
//Hieronder moet er xml worden ingeladen
glBegin(GL_QUADS);
// Bottom Face
glNormal3f( 0.0f,-1.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
// Front Face
glNormal3f( 0.0f, 0.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f);
// Back Face
glNormal3f( 0.0f, 0.0f,-1.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
// Right face
glNormal3f( 1.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
// Left Face
glNormal3f(-1.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);
glEnd();
glEndList();
}
}
//functie die zorgt dat we renderen in selectiemode
void GLWidget::renderInSelectionMode() {
glInitNames(); //Creates empty stack
glPushName(1); //Push a name on the stack
//draw something
glColor3f(1.0f,0.0f,0.0f);
glCallList(displayList[0]);
glPopName(); //pop a name from the stack
glPushName(2); //Push a name on the stack
//draw something
glTranslatef(5.0,0.0,0.0);
glColor3f(0.0f,1.0f,1.0f);
glCallList(displayList[0]);
glPopName(); //Pops a name from the stack
}
void GLWidget::startPicking() {
GLint viewport[4];
glSelectBuffer(BUFSIZE,selectBuf);
glRenderMode(GL_SELECT);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glGetIntegerv(GL_VIEWPORT,viewport);
gluPickMatrix(cursorX,viewport[3]-cursorY,5,5,viewport);
gluPerspective(45,aspect_ratio,0.1,1000);
glMatrixMode(GL_MODELVIEW);
glInitNames();
}
void GLWidget::stopPicking() {
int hits;
// restoring the original projection matrix
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glFlush();
// returning to normal rendering mode
hits = glRenderMode(GL_RENDER);
// if there are hits process them
if (hits != 0)
processHits(hits,selectBuf);
}
void GLWidget::processHits (GLint hits, GLuint buffer[])
{
unsigned int i, j;
GLuint names, *ptr, minZ,*ptrNames, numberOfNames;
printf ("hits = %d\n", hits);
ptr = (GLuint *) buffer;
minZ = 0xffffffff;
for (i = 0; i < hits; i++) {
names = *ptr;
ptr++;
if (*ptr < minZ) {
numberOfNames = names;
minZ = *ptr;
ptrNames = ptr+2;
}
ptr += names+2;
}
printf ("The closest hit names are ");
ptr = ptrNames;
for (j = 0; j < numberOfNames; j++,ptr++) {
printf ("%d ", *ptr);
}
printf ("\n");
}
void GLWidget::mousePressEvent(QMouseEvent * e)
{
if(e->button() == Qt::LeftButton)
{
qDebug("mouse");
qDebug("%d",QCursor::pos().x());
this->cursorX = QCursor::pos().x();
this->cursorY = QCursor::pos().y();
this->mode = 2;
}
}
void GLWidget::keyPressEvent( QKeyEvent * e ) {
double fraction = 0.1f;
if(e->key() == Qt::Key_Up)
{
camPosz += camViewz * fraction;
camPosx += camViewx * fraction ;
}
if(e->key() == Qt::Key_Down)
{
camPosz -= camViewz * fraction;
camPosx -= camViewx * fraction ;
}
if(e->key() == Qt::Key_Left)
{
camAngle -= 0.05f;
camViewz = -cos(camAngle);
camViewx = sin(camAngle);
}
if(e->key() == Qt::Key_Right)
{
qDebug("cam angle is %f", camAngle);
camAngle +=0.05f;
camViewz = -cos(camAngle);
camViewx = sin(camAngle);
}
}
#ifndef GLWIDGET_H
#define GLWIDGET_H
#include <QtOpenGL/QGLWidget>
#include <gl/GLU.h>
#include <QImage>
#include <QKeyEvent>
#include <QMouseEvent>
#include <QTimer>
#define BUFSIZE 512
class GLWidget: public QGLWidget
{
Q_OBJECT
public:
GLWidget(QWidget *parent = NULL);
private:
double camPosx,camPosy,camPosz;
double camUpx,camUpy,camUpz;
double camViewx,camViewy,camViewz;
double camAngle;
protected:
void initializeGL();
void resizeGL(int width, int height);
void paintGL();
void keyPressEvent(QKeyEvent * e);
void mousePressEvent(QMouseEvent * e);
QTimer* timer;
void loadGLTextures();
GLuint texture[1];
GLuint * displayList;
void renderInSelectionMode();
GLvoid buildLists(int aantal);
void startPicking();
void stopPicking();
void processHits (GLint hits, GLuint buffer[]);
GLuint selectBuf[BUFSIZE];
GLdouble aspect_ratio;
int cursorY;
int cursorX;
int mode;
};
#endif // GLWIDGET_H
this is the normal view without clicking once
http://imageshack.us/photo/my-images/233/31536776.png/
then when clicked it keeps getting in startpicking and stop picking and gives a black screen
http://imageshack.us/photo/my-images/13/14180995.png/
and then after closing the window so it stops running it gives me this output http://imageshack.us/photo/my-images/861/13486229.png/
Could be wrong, but it looks like you aren't resetting your mode-variable back to 1 after the first mouseclick anywhere, so the start- & stopPicking-methods are called on each frame from the first click onwards. If that's not the case, then you probably have some problem with gl-states/matrices not all being reset correctly after the picking.

OpenGL texture inverted

I'm trying to map the input from my webcam to a plane in OpenGL. I'm using OpenCV to get the images from the webcam.
The problem I have is that the texture is vertically inverted, if my texture is "v", the current result is "^".
I want to fit the image taken from the webcam to my plane (2x2). Its lower left corner is -1, -1 and the upper right corner is 1,1.
The code is:
const int VIEWPORT_WIDTH = 640;
const int VIEWPORT_HEIGHT = 480;
const int KEY_ESCAPE = 27;
CvCapture* g_Capture;
IplImage* image;
GLint g_hWindow;
GLvoid InitGL();
GLvoid OnDisplay();
GLvoid OnReshape(GLint w, GLint h);
GLvoid OnKeyPress (unsigned char key, GLint x, GLint y);
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowPosition(100, 100);
glutInitWindowSize(VIEWPORT_WIDTH, VIEWPORT_HEIGHT);
g_hWindow = glutCreateWindow("Image");
image = cvLoadImage("average.jpg", 1);
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, image->width, image->height, GL_RGB, GL_UNSIGNED_BYTE, image->imageData);
InitGL();
glutMainLoop();
return 0;
}
GLvoid InitGL()
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glutDisplayFunc(OnDisplay);
glutReshapeFunc(OnReshape);
glutKeyboardFunc(OnKeyPress);
}
GLvoid OnDisplay(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
glPushMatrix();
glTranslatef(0.0f, 0.0f, -2.5f);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glEnd();
glPopMatrix();
glutSwapBuffers();
}
GLvoid OnReshape(GLint width, GLint height)
{
if (height==0)
height=1;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(0, 0, width, height);
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height, 1.0f, 10.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt( 0.0, 0.0, 0.0, 0.0, 0.0, -6.0, 0.0f, 1.0f, 0.0f);
}
GLvoid OnKeyPress(unsigned char key, int x, int y)
{
switch (key) {
case KEY_ESCAPE:
cvReleaseImage(&image);
glutDestroyWindow(g_hWindow);
exit(0);
break;
}
glutPostRedisplay();
}
BTW. In this code I'm loading an image instead of getting from the webcam.
Any suggestion?
Flip the texture coordinates on the quad you're rendering. OpenGL does store texture "upside-down" from how most people assume they'd be, so the simplest way to handle it is just work with OGL.
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
should do it, I think.