[Interest] Qt5 QML OpenGL and "black" texture problem

[BOUCARD Olivier]

Hi guys,

I'm trying to display some "native" OpenGL inside a custom QML item using 
Qt 5.0.2 on a Linux x86_64 with a Nvidia 9600M GT (driver v295.40).
I have a custom QQuickPaintedItem with a overloaded paint where I use 
painter->beginNativePainting() and a shader program:

Vertex shader:

uniform highp mat4 projectionMatrix;
uniform highp mat4 modelViewMatrix;

void main(void)
{
  gl_Position = projectionMatrix * modelViewMatrix * gl_Vertex;
  gl_FrontColor = gl_Color;
  gl_TexCoord[0] = gl_MultiTexCoord0;
}



Fragment shader:

uniform highp sampler2D diffuseTexture;

void main(void)
{
  gl_FragColor = texture2D(diffuseTexture, gl_TexCoord[0].st);
  //gl_FragColor = gl_Color; // Display the mesh in white -> OK

  //gl_FragColor = vec4(gl_TexCoord[0].st, 0.0, 1.0); // Display the correct 
coord -> OK
}



I have a mesh class used to load a mesh using Assimp. At the moment I only load 
a simple cube.obj.
The rendering code is the following:

void Mesh::render()
{
  if(mData->hasDiffuse)
  {
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, mData->diffuse);
  }

  glEnableVertexAttribArray(SimpleGameEngine::sAttrLocVertex);
  glEnableVertexAttribArray(SimpleGameEngine::sAttrLocTex0);
  glBindBuffer(GL_ARRAY_BUFFER, mData->vertexBuffer);
  glVertexAttribPointer(SimpleGameEngine::sAttrLocVertex, 3, GL_FLOAT, 
GL_FALSE, 0, NULL);

  glBindBuffer(GL_ARRAY_BUFFER, mData->texBuffer);
  glVertexAttribPointer(SimpleGameEngine::sAttrLocTex0, 2, GL_FLOAT, GL_FALSE, 
0, NULL);

  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mData->faceBuffer);
  glDrawElements(GL_TRIANGLES, mData->faceNum * 3,GL_UNSIGNED_INT, 0);

  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
  glBindBuffer(GL_ARRAY_BUFFER, 0);
  glDisableVertexAttribArray(SimpleGameEngine::sAttrLocTex0);
  glDisableVertexAttribArray(SimpleGameEngine::sAttrLocVertex);

  if(mData->hasDiffuse)
  {
    glBindTexture(GL_TEXTURE_2D, 0);
    glActiveTexture(GL_TEXTURE0);
  }
}

My texture is loaded using the following code:

void Mesh::setDiffuseTexture(const QImage &image)
{
  if(image.isNull()) qFatal("Invalid image");

  QImage texture = QGLWidget::convertToGLFormat(image);

  if(texture.isNull()) qFatal("Invalid texture");

  glGenTextures(1, &mData->diffuse);

  glBindTexture(GL_TEXTURE_2D, mData->diffuse);

  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, texture.width(), texture.height(), 
0, GL_RGBA, GL_UNSIGNED_BYTE, texture.bits());

  glBindTexture(GL_TEXTURE_2D, 0);

  mData->hasDiffuse = true;
}

Everything works. But as soon as I add the texture my cube turns black.
I already try with a procedural 4x4 checker texture and it didn't work either.


Any help will be appreciated.
Olivier. 

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