Seriously don't understand WHY my framebuffer isn't rendering as a texture

Lil_Lloyd · 2012-07-24T20:04:59

Ok so I've looked at several tutorials and checked my code but something VERY simple must be eluding me here. I render a rotating teapot to a texture and then try and render this texture as a full screen quad, just to get used to framebuffers before doing anything fancy with them. I have tested rendering the teapot straight to the screen, that was ok. I has tested my quad shading code by making the screen yellow in a fragment shader, that was ok too. However when trying to render to the texture I just don't get the results I want! I get NOTHING! I have a framebuffer struct, and a helper function to set up a FBO as required: typedef struct { GLubyte * imageData; GLuint bpp; GLuint width; GLuint height; GLuint texID; GLuint type; } Texture; typedef struct { GLuint handle; GLuint depthBuffer; GLint depthHeight; GLint depthWidth; Texture textureData; Texture nonTexture; }FBO; void FrameBufferObject(FBO& fboData,GLenum minFilter,GLenum magFilter) { glGenFramebuffers(1,&fboData.handle); glBindFramebuffer(GL_FRAMEBUFFER,fboData.handle); glGenTextures(1,&fboData.textureData.texID); glBindTexture(GL_TEXTURE_2D,fboData.textureData.texID); glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,fboData.depthWidth,fboData.depthHeight,0,GL_RGBA,GL_UNSIGNED_BYTE,NULL); 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_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glGenRenderbuffers(1,&fboData.depthBuffer); glBindRenderbuffer(GL_RENDERBUFFER,fboData.depthBuffer); glRenderbufferStorage(GL_RENDERBUFFER,GL_DEPTH_COMPONENT,fboData.depthWidth,fboData.depthHeight); glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,GL_RENDERBUFFER,fboData.depthBuffer); glFramebufferTexture(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,fboData.textureData.texID,0); GLenum drawBufs[] = {GL_COLOR_ATTACHMENT0}; glDrawBuffers(1,drawBufs); if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) std::cout<<"problem with framebuffer!"; else std::cout<<"framebuffer ok! "; glBindFramebuffer(GL_FRAMEBUFFER,0); } my shader code is as follows: //texture.vp #version 330 in vec3 position; out vec2 UV; void main() { gl_Position = vec4(position,1); UV = (position.xy+vec2(1,1))/2.0; } //texture.fp #version 330 in vec2 UV; out vec3 color; uniform sampler2D renderedTexture; void main() { color = texture(renderedTexture,UV).rgb; } I call my rendering code as follows... void RenderToTexture() { glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT ); glUseProgram(renderProgram); glUniformMatrix4fv(MVPMatrixUniform,1,GL_FALSE,&MVPMatrix[0][0]); glEnableVertexAttribArray(0); //set variables for the fbo glBindFramebuffer(GL_FRAMEBUFFER,frameBuf.handle); glViewport(0,0,512,512); GLenum drawBufs[] = {GL_COLOR_ATTACHMENT0}; glDrawBuffers(1,drawBufs); teapot->render(); glUseProgram(0); glDisableVertexAttribArray(0); glBindFramebuffer(GL_FRAMEBUFFER,0); } void DrawTextureToQuad() { glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT ); glViewport(0,0,640,480); glUseProgram(textureProgram); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D,frameBuf.textureData.texID); GLuint texID = glGetUniformLocation(textureProgram, "renderedTexture"); glUniform1i(texID,0); glEnableVertexAttribArray(0); //Render to the screen glBindBuffer(GL_ARRAY_BUFFER, quad_vertexbuffer); glVertexAttribPointer( 0, // attribute 0. No particular reason for 0, but must match the layout in the shader. 3, // size GL_FLOAT, // type GL_FALSE, // normalized? 0, // stride (void*)0 // array buffer offset ); // Draw the triangle ! glDrawArrays(GL_TRIANGLES, 0, 6); // From index 0 to 3 -> 1 triangle glDisableVertexAttribArray(0); glUseProgram(0); } void DrawGLScene(GLvoid) { MVPMatrix = perspMatrix * camMatrix * transformMatrix; Update(); RenderToTexture(); DrawTextureToQuad(); glutSwapBuffers(); glutPostRedisplay(); } If anyone can help, I'd be really grateful!

Graphics and GPU Programming Programming

Started by Lil_Lloyd July 11, 2012 03:48 AM

23 comments, last by Ignifex 11 years, 8 months ago

Lil_Lloyd

287

Author

July 13, 2012 07:45 AM

can you please upload glbatch.h and gltools.h as well?

Just comment those lines out of the includes.h file, they are not used. Sorry!

Yours3!f

1,534

July 13, 2012 07:54 AM

[quote name='Yours3!f' timestamp='1342164568' post='4958686']
can you please upload glbatch.h and gltools.h as well?

Just comment those lines out of the includes.h file, they are not used. Sorry!
[/quote]

ok, I did and my Catalyst driver crashes at this if statement:

if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)

		 std::cout<<"problem with framebuffer!";

     else

         std::cout<<"framebuffer ok! ";

you're doing something really wrong

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Yours3!f

1,534

July 13, 2012 08:00 AM

ok, now it starts, my compiler fuzzed up something... but I can only see a pink screen.

Blog:

http://extremeistan.wordpress.com/

Stuff I wrote:

https://github.com/Yours3lf/libmymath

https://github.com/Yours3lf/linux_gl_fps

https://github.com/Yours3lf/instanced_font_rendering

http://youtu.be/k8PYkihyGXA

https://github.com/scrawl/smaa-opengl

https://github.com/Yours3lf/gl_browser_gui

Follow me on twitter:

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Lil_Lloyd

287

Author

July 13, 2012 09:59 AM

ok, I did and my Catalyst driver crashes at this if statement:
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
std::cout<<"problem with framebuffer!";
else
std::cout<<"framebuffer ok! ";
you're doing something really wrong

That's the thing that bugs me, my framebuffer is 'complete' as the framebuffer ok message always prints to the std output

Ignifex

520

July 24, 2012 08:04 PM

Could you try adding a glDrawBuffer(GL_BACK); before rendering to the backbuffer? If your texture appears correctly in gDebugger, the problem should be in the second drawing step.

Seriously don't understand WHY my framebuffer isn't rendering as a texture

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Seriously don't understand WHY my framebuffer isn't rendering as a texture

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