Can't render to texture (anymore) - opengl

Question

I implemented a volume rendering demo application a few months ago. Everything worked fine in Windows XP-32bits. I used OpenGL -glew and SFML2.0-rc as a windowing&input library.
Now. I moved to windows 7-64bits just recently.
The program did not work out of the box, SFML seemed to crash. I changed the windowing library to GLFW, still using Glew. By going through the code i realized the very basic render to texture technique did not work anymore.
So i broke everything down to a minimal case so i could present it to you. (I also made a port to Qt5.0.2 to cross-check my assumptions : same diagnosis).
So here is the problem :
The program is supposed to render a simple unit cube with front-face culling to a texture in pass 1. Then in pass 2 i switch to back-face culling and render the same cube again. In the fragment shader (pass 2) i have the option to read the texture (from pass 1) and write it to the output : but i get a big black screen when i should see the front-face culled cube ...
Initialization code :
glGenFramebuffers(1, &raycastingFrameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, raycastingFrameBuffer);
glGenTextures(1, &cubeRenderTexture);
glBindTexture(GL_TEXTURE_2D, cubeRenderTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, viewWidth, viewHeight, 0, GL_RGBA, GL_FLOAT, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, cubeRenderTexture, 0);
GLenum DrawBuffers[1] = {GL_COLOR_ATTACHMENT0};
glDrawBuffers(1, DrawBuffers);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
return false;
glBindFramebuffer(GL_FRAMEBUFFER, 0);
Render passes :
// PASS ONE :
// render the unit cube (with front face culling) to texture
// we end up with a texture whose colors represent outgoing rays locations on the box
//
glBindFramebuffer(GL_FRAMEBUFFER, raycastingFrameBuffer);
glEnable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glViewport(0, 0, viewWidth, viewHeight);
glCullFace(GL_FRONT);
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(shaderRaycasting1.getProgramID());
glBindBuffer(GL_ARRAY_BUFFER, cube_VBO_ID);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (char*)NULL + 0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, (char*)NULL + 108*sizeof(float));
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glUniformMatrix4fv(glGetUniformLocation(shaderRaycasting1.getProgramID(), "modelview"), 1, GL_TRUE, modelview.getData());
glUniformMatrix4fv(glGetUniformLocation(shaderRaycasting1.getProgramID(), "projection"), 1, GL_TRUE, projection.getData());
glDrawArrays(GL_TRIANGLES, 0, 36);
glDisableVertexAttribArray(1);
glDisableVertexAttribArray(0);
glUseProgram(0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glEnable(GL_DEPTH_TEST);
// PASS TWO :
// render the unit cube (with back face culling this time)
// we get colors representing ray entrance locations on the box
//
glViewport(0, 0, viewWidth, viewHeight);
glCullFace(GL_BACK);
glClearColor(0.0, 0.0, 0.0, 0.0);
glClearDepth(1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(shaderRaycasting2.getProgramID());
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, cubeRenderTexture);
glUniform1i(cubeRenderTextureID, 0);
glUniform1i(glGetUniformLocation(shaderRaycasting2.getProgramID(), "displayWidth"), (GLint) viewWidth);
glUniform1i(glGetUniformLocation(shaderRaycasting2.getProgramID(), "displayHeight"), (GLint) viewHeight);
glBindBuffer(GL_ARRAY_BUFFER, cube_VBO_ID);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (char*)NULL + 0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, (char*)NULL + 108*sizeof(float));
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glUniformMatrix4fv(glGetUniformLocation(shaderRaycasting1.getProgramID(), "modelview"), 1, GL_TRUE, modelview.getData());
glUniformMatrix4fv(glGetUniformLocation(shaderRaycasting1.getProgramID(), "projection"), 1, GL_TRUE, projection.getData());
glDrawArrays(GL_TRIANGLES, 0, 36);
glDisableVertexAttribArray(1);
glDisableVertexAttribArray(0);
glActiveTexture(0);
glUseProgram(0);
... and finally the minimal fragment shader :
#version 330
in vec3 color;
uniform int displayWidth;
uniform int displayHeight;
uniform sampler2D cubeTex;
layout (location = 0) out vec4 outColor;
void main()
{
float viewWidth = displayWidth;
float viewHeight = displayHeight;
vec3 boxIn = color;
vec2 cubeCoord = vec2( (gl_FragCoord.x - 0.5) / viewWidth, (gl_FragCoord.y - 0.5) / viewHeight);
vec3 boxOut = texture(cubeTex, cubeCoord).rgb;
vec3 rayColor = boxOut;
outColor = vec4(rayColor, 1); // i get a black screen here ...
}
Some last words :
- Everything compiles with no warnings, no errors (same for Qt 5.0.2 port of the demo)
- I tried every possible little "tweaking" like glEnable(...), changing opengl version, using texelFetch, and what not ... obviously i can't find what's wrong with this code.
- The original code was much more complex and did run, but on XP and not on Win7.
- etc.

Answer 1

Did you install the original vendor drivers for your GPU as downloaded from the vendor's driver support website, or do you still have installed the crippled versions that are shipped with Windows 7?
The drivers shipping with Windows 7 do not offer modern OpenGL support. Microsoft strips them of anything OpenGL and the default OpenGL implementation of Windows-7 is just a OpenGL-1.4 emulation on top of Direct3D.
If you didn't already, then download the original drivers from your GPU's vendor and install those, then report back if this changed the outcome.