I wrote the following code snippet to bind a bitmap to texture. I got an ordinary buffer filled it with some values and then assigned it as a parameter to create a 800 * 600 texture. However, whatever values I assign to buffer, the screen remains white with some black tracks, n sometimes becomes awful. I don't where I am doing wrong:

Qt Code: 
  1. struct Texture
  2. {
  3.     GLuint id;
  4.     unsigned char* buf;
  5. };
  6.  
  7.  tex.buf = new unsigned char[800*600];
  8.     for(int i = 0; i < 800*600 - 1; i++)
  9.         tex.buf[i] = 0;
To copy to clipboard, switch view to plain text mode 


and here I create the texture using the above buffer:

Qt Code: 
  1. void GlWidget::createTextureFromBitmap(QByteArray bytes)
  2. {
  3.   /* create a 800 bye 600 texture from bitmap */
  4.  
  5. //    tex.buf = new unsigned char[bytes.size()];
  6.  
  7. //    memcpy(tex.buf, bytes.constData(), bytes.size());
  8.  
  9.     tex.id = 1;
  10.  
  11.     glBindTexture(GL_TEXTURE_2D, tex.id);
  12.     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  13.     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  14.     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR);
  15.     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_LINEAR);
  16.     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  17.  
  18.     glTexImage2D(     GL_TEXTURE_2D, 0, GL_RGB, 0, 0, 0, GL_RGB, GL_UNSIGNED_BYTE, tex.buf);
  19.  
  20.     gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, 800, 600, GL_RGB, GL_UNSIGNED_BYTE, tex.buf);
  21.  
  22. //    delete [] tex.buf;
  23.  
  24. //    tex.buf = NULL;
  25.  
  26.     updateGL();
  27. }
To copy to clipboard, switch view to plain text mode 

in the painGL function, I also render texture to the screen using the commands below:

Qt Code: 
  1. void GlWidget::paintGL()
  2. {
  3.     //! [5]
  4.     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  5.  
  6.     QMatrix4x4 mMatrix;
  7.     QMatrix4x4 vMatrix;
  8.  
  9.     QMatrix4x4 cameraTransformation;
  10.     //    cameraTransformation.rotate(alpha, 0, 1, 0);
  11.     //    cameraTransformation.rotate(beta, 1, 0, 0);
  12.  
  13.     QVector3D cameraPosition = cameraTransformation * QVector3D(0, 0, distance);
  14.     QVector3D cameraUpDirection = cameraTransformation * QVector3D(0, 1, 0);
  15.  
  16.     vMatrix.lookAt(cameraPosition, QVector3D(0, 0, 0), cameraUpDirection);
  17.  
  18.     //! [6]
  19.     shaderProgram.bind();
  20.     shaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
  21.     shaderProgram.setUniformValue("texture", 0);
  22.  
  23.  
  24.     glActiveTexture(GL_TEXTURE0);
  25.     glBindTexture(GL_TEXTURE_2D, tex.id);
  26.     glActiveTexture(0);
  27.  
  28.  
  29.     shaderProgram.setAttributeArray("vertex", vertices.constData());
  30.     shaderProgram.enableAttributeArray("vertex");
  31.     shaderProgram.setAttributeArray("textureCoordinate", textureCoordinates.constData());
  32.     shaderProgram.enableAttributeArray("textureCoordinate");
  33.  
  34.     glDrawArrays(GL_TRIANGLES, 0, vertices.size());
  35.  
  36.     shaderProgram.disableAttributeArray("vertex");
  37.     shaderProgram.disableAttributeArray("textureCoordinate");
  38.     shaderProgram.release();
  39. }
To copy to clipboard, switch view to plain text mode