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Thread: create texture from bitmap

  1. #1
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    Default create texture from bitmap

    I wan to create texture from image rgb data. When the texture is rendered to the screen it shows nothing. I was just wondering if I missed something in the implementation:

    Qt Code:
    1. void GlWidget::createTextureFromBitmap(QByteArray btmp)
    2. {
    3. /* create a 800 bye 600 * 3 texture from bitmap */
    4. tex.buf = new unsigned char[bytes.size()];
    5. memcpy(tex.buf, bytes.constData(), bytes.size());
    6. glGenTextures( 1, &tex.id);
    7. glBindTexture(GL_TEXTURE_2D, tex.id);
    8. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    9. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    10. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR);
    11. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_LINEAR);
    12. glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    13. glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, 0, 0, 0, GL_RGB, GL_UNSIGNED_BYTE, tex.buf);
    14. gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, 800, 600, GL_RGB, GL_UNSIGNED_BYTE, tex.buf);
    15. delete [] tex.buf;
    16. tex.buf = NULL;
    17.  
    18. updateGL();
    19. }
    20.  
    21.  
    22. void GlWidget::paintGL()
    23. {
    24. shaderProgram.bind();
    25. shaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
    26. shaderProgram.setUniformValue("texture", 0);
    27.  
    28. glActiveTexture(GL_TEXTURE0);
    29. glBindTexture(GL_TEXTURE_2D, tex.id);
    30. //glActiveTexture(0);
    31.  
    32. shaderProgram.setAttributeArray("vertex", vertices.constData());
    33. shaderProgram.enableAttributeArray("vertex");
    34. shaderProgram.setAttributeArray("textureCoordinate", textureCoordinates.constData());
    35. shaderProgram.enableAttributeArray("textureCoordinate");
    36.  
    37. glDrawArrays(GL_TRIANGLES, 0, vertices.size());
    38.  
    39. shaderProgram.disableAttributeArray("vertex");
    40. shaderProgram.disableAttributeArray("textureCoordinate");
    41. shaderProgram.release();
    42. }
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  2. #2
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    Default Re: create texture from bitmap

    If it shows nothing then maybe your drawing code is invalid. Does it render correctly if you replace the texture with a solid color?
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  3. #3
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    Default Re: create texture from bitmap

    Quote Originally Posted by wysota View Post
    If it shows nothing then maybe your drawing code is invalid. Does it render correctly if you replace the texture with a solid color?
    It is fine now. I needed to adjust the camera position.
    Last edited by saman_artorious; 11th January 2014 at 15:14.

  4. #4
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    Default Re: create texture from bitmap

    A GL texture is perfectly scalable, it is not composed of pixels.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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