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Thread: find the location of texture uniform

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  1. #1
    Newbie Newbie
    Join Date
    Nov 2012

    Question find the location of texture uniform

    Hi ,here is my glsl code
    Code :
    #version 400
    in vec4 ex_Color;
    in vec4 ex_Pos;
    out vec4 FragColor;
    uniform sampler2D RayStartPoint;
    uniform sampler2D RayStopPoint;
    void main()
      vec4 temp = ex_Color;
      vec2 texc = ((ex_Pos.xy / ex_Pos.w) + 1.0f )/2.0f ;  
      vec4 startPosition  = texture(RayStartPoint, texc) ;
      vec4 stopPosition  = texture2D(RayStopPoint, texc);
       temp.w = 1 ;   
     // FragColor = startPosition ;
    	FragColor = stopPosition ;
     // FragColor = temp ;
     //  FragColor = stopPosition -  startPosition ;
    my program could find the first uniform location,but can't find the second. the function "glGetUniformLocation" just return -1
    anyone had encountered similar problem?

  2. #2
    Senior Member OpenGL Pro
    Join Date
    Jan 2012
    You are not using the uniform in the code so it is optimised away. You always have to be able to cope with -1 return. It is usually any error - unless you are testing when it is really a pain!

  3. #3

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