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View Full Version : find the location of texture uniform



bingdianlieshou
11-05-2012, 06:11 PM
Hi ,here is my glsl 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?

tonyo_au
11-05-2012, 07:50 PM
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!

Alfonse Reinheart
11-05-2012, 07:51 PM
Cross-posting isn't helping.