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

[BOUCARD Olivier]

Thanks Sletta for this great input.

Adding the texture parameter resolve the problem.
I though this was not mandatory.

But I will definitively look at your example as I have a weird problem when I try to update a rotation angle at each frame instead of having a static one.

Cheers,
Olivier




>________________________________
> De : Sletta Gunnar <Gunnar.Sletta at digia.com>
>À : BOUCARD Olivier <boucard_olivier at yahoo.fr> 
>Cc : "interest at qt-project.org" <interest at qt-project.org> 
>Envoyé le : Jeudi 2 mai 2013 14h46
>Objet : Re: [Interest] Qt5 QML OpenGL and "black" texture problem
> 
>
>You are at least not setting the required texture parameters which will make the texture incomplete. You typically need to set the textures wrap and min/mag filters at least once: 
>
>glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
>glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
>glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
>glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
>
>btw, I would think the "Scene Graph - Rendering FBOs" example I added for 5.1 is a good starting place for implementing what you are trying to do here: http://doc-snapshot.qt-project.org/qt5-stable/qtquick/scenegraph-textureinsgnode.html
>
>cheers,
>Gunnar
>
>
>On May 2, 2013, at 12:31 PM, BOUCARD Olivier <boucard_olivier at yahoo.fr> wrote:
>
>> 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. 
>> 
>> _______________________________________________
>> Interest mailing list
>> Interest at qt-project.org
>> http://lists.qt-project.org/mailman/listinfo/interest
>
>
>
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