FBO and Render To Texture = no alpha ?
Author
hi guys,
i'm trying to do a simple RTT - render to texture - with a FBO - frame buffer object -.
I can manage to do it, but it does not work whenever the texture has alpha : e.g. it seems the alpha is not copyed into the FBO. So the RTT works but wihtout
the "alpha channel".
Could you guys tell me how do i do an RTT with an FBO when my texture has alpha ?
many thanks in advance.
Author
up
i've been trying to do the following, but no effect at all (i use a shader so that's why the scene rendering contains "passes") :
any advice on that ?
thank you ...
[Edited by - carmellose on October 11, 2008 4:42:06 AM]
i've been trying to do the following, but no effect at all (i use a shader so that's why the scene rendering contains "passes") :
void DrawObject(void) { glClear(GL_COLOR_BUFFER_BIT); glLoadIdentity(); /* draw a simple triangle and bind texture coordinates */ glPushMatrix(); glBegin(GL_TRIANGLES); glTexCoord3f(0, 0, -1); glVertex3f(-0.8, 0.8, -1); glTexCoord3f(1, 0, -1); glVertex3f(0.8, 0.8, -1); glTexCoord3f(0.5, 1, -1); glVertex3f(0.0, -0.8, -1); glEnd(); glPopMatrix();}void RenderToTexture (void) { // create objects glGenFramebuffersEXT(1, &myFBO);// frame buffer glGenRenderbuffersEXT(1, &myRBF);// frame buffer glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, myFBO); // initialize texture glBindTexture(GL_TEXTURE_2D, TEX_SCENE_SOURCE_IMAGE ); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, sourceW, sourceH, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // attach texture to framebuffercolor buffer glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, TEX_SCENE_SOURCE_IMAGE, 0); // initialize depth renderbuffer glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, myRBF); glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGBA ,sourceW ,sourceH); // attach renderbuffer to framebufferdepth buffer glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, myRBF); CHECK_FRAMEBUFFER_STATUS(); //render to the FBO glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, myFBO); // (draw something here, rendering to texture) glPushAttrib(GL_VIEWPORT_BIT); glViewport(0,0,sourceW,sourceH ); DrawObject(); glPopAttrib(); // render to the window, using the texture glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); glBindTexture(GL_TEXTURE_2D, TEX_SCENE_SOURCE_IMAGE );}/* * main routine to display openGL scene * */void DrawGLScene(void) { CGpass pass; if ( t++ == 0) { printf("[+] Render To Texture ...\n"); RenderToTexture(); } pass = cgGetFirstPass(cgTechnique); while(pass) { cgSetPassState(pass); /* Draw the scene as a texture */ glBegin(GL_QUADS); 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); glEnd(); cgResetPassState(pass); pass = cgGetNextPass(pass); } glPopMatrix(); glutSwapBuffers(); return; }any advice on that ?
thank you ...
[Edited by - carmellose on October 11, 2008 4:42:06 AM]
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