OpenGL scale texture coordinates



  • Hi
    I use opengl shader for apply median filter to image. Input image I copy to in_fbo buffer. All work fine.

    	QGLFramebufferObject *in_fbo, *out_fbo;
        out_fbo->bind();
    	glViewport( 0, 0, nWidth, nHeight );
    	glMatrixMode( GL_PROJECTION );
    	glLoadIdentity();
    
    	glOrtho( 0.0, nWidth, 0.0, nHeight, -1.0, 1.0 );
    
    	glMatrixMode( GL_MODELVIEW );
    	glLoadIdentity( );
    
    	glEnable( GL_TEXTURE_2D );
    
    	out_fbo->drawTexture( QPointF(0.0,0.0), in_fbo->texture( ), GL_TEXTURE_2D );
    

    But in shader code I need divide position of vertex by width and height of image, because texture coordinates are normalized to a range between 0 and 1.

    vec2 texCoord = vec2( pos.x / float( imgWidth ), pos.y / float( imgHeight ) );
    

    How I can scale texture coordinates? I want have texture coordinates in range between 0 and imgWidth, It is important for me.


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