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OpenGL render to texture and glClearColor problem

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carmellose    122
hi guys, i managed to do a simple render to texture of a series of cubes. I believed it worked, but when i tryed to change the background color of the texture i saw it does not. Actually, i try to set the bg color to green in the texture, but it has absolutly no effect. here's my code (the relevant parts) :
void DrawObject(void) {

	int i;
	float z=3;
	 * The texture defined in a FBO carries its own
	 * viewport. So here we define the viewport and
	 * initilizations that needs to come with it.


        // ===> HEre i tryed to set the background to green .... no effect at all ?!?!??
	 * draw objects here







#define NOBJECTS (6)
	for (i=0;i<NOBJECTS;++i) {


		glVertex3f( 1.0f, 1.0f,-1.0f);			
		glVertex3f(-1.0f, 1.0f,-1.0f);		
		glVertex3f(-1.0f, 1.0f, 1.0f);	
		glVertex3f( 1.0f, 1.0f, 1.0f);

		//etc for the rest of the faces ...
                // ...
                // ...

	//revert to previous modelview matrix
	//revert to previous projection matrix
	//switch back to the modelview 


void RenderToTexture (void) {

        //FBO initialization ...
        // ...
        // ...

	 * 	Render To Texture 
	// (draw something here, rendering to texture)
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, myFBO);
	glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, myDBO);
	//Bind 0, which means render to back buffer
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0);


 * main routine to display openGL scene
 * */
void DrawGLScene(void) {


	/* Draw the scene as a texture */


	glTexCoord3f (0, 0, -1);
	glVertex3f	 (-1,1 , -1);
	glTexCoord3f (1, 0, -1);
	glVertex3f	 (1, 1, -1);
	glTexCoord3f (1, 1, -1);
	glVertex3f	 (1, -1, -1);
	glTexCoord3f (0, 1, -1);
	glVertex3f	 (-1, -1, -1);


 * Init the GL runtime
 * */
bool GLInit(void) {	


	glPixelStorei(GL_UNPACK_ALIGNMENT, 1); /* Tightly packed texture data. */

	glClearColor(0, 1, 0, 0);  

	return true;

what did i do wrong ? i don't get it! thanks in advance if anyone has ideas cheers

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Gorax    202
The problem you're facing is quite simple. You don't render anything when clear the buffer. If you want a green background, disable depth testing, then render a single quad that will fill the entire screen, and that will render the green background you're looking for.

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carmellose    122
Original post by Gorax
The problem you're facing is quite simple. You don't render anything when clear the buffer. If you want a green background, disable depth testing, then render a single quad that will fill the entire screen, and that will render the green background you're looking for.

does that mean i can't use glClearColor/glClear when rendering to a texture ??!?

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