GLSL: troubles with uniform float variables

OpenGL OpenGL: Basic Coding
1

Hi all!

I’m coding via Debian 6.0.1, C (without C++).
Also I use GLSL shaders. And I have a problem here: all uniform variables with float(vec2, vec3, vec4) types always is zero in my shaders. But “int” and “sampler2D” is ok.

What’s can be wrong there?

Thanks!

Best regards, Serge.

2

Probably because you didn’t set them correctly. For more elaborated answer more information about the problem is needed.

3

Ok!
I don’t make any differents between settings the “int” and “float” variables.
So, in the program this:


glUniform1fARB(glGetUniformLocationARB(gv_Shader_Test, "MY_FLOAT_VAR"), 10.0);
glUniform1iARB(glGetUniformLocationARB(gv_Shader_Test, "MY_INT_VAR"), 25);

In the shader it seems like this:


uniform float MY_FLOAT_VAR;
uniform int MY_INT_VAR;

void main(void)
{
  vec3 color = vec3(1.0, 0.5, 0.25);
  gl_FragColor = vec4(color, 1.0);
}

Also I have a script(#1) in my program:


char *s = (char*)malloc(255);
int l = 0;
int i = 0;
for(i = 0; i < 5; i++)
{
  glGetActiveUniformName(gv_Shader_Test, i, 255, &l, s);
  if(s != NULL)
  {
    printf("
l = %i, s = \"%s\"", l, s);
  }
}

When I don’t use the variables in the shader, the script #1 returns:


l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"

Then I apply the changes to the fragment-shader:


void main(void)
{
  vec3 color = vec3(1.0, 0.5, 0.25);
  color /= MY_INT_VAR;

  gl_FragColor = vec4(color, 1.0);
}

The script #1 returns:


l = 10, s = "MY_INT_VAR"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"

That is ok! When I’m setting different values to MY_INT_VAR, I’m getting different colors.

Then I apply another changes to the fragment-shader:


void main(void)
{
  vec3 color = vec3(1.0, 0.5, 0.25);
  color /= MY_FLOAT_VAR;

  gl_FragColor = vec4(color, 1.0);
}

So, I have:


l = 12, s = "MY_FLOAT_VAR"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"
l = 37, s = "gl_ModelViewProjectionMatrixTranspose"

But in the shader MY_FLOAT_VAR is always zero. So, I’m setting different values to MY_FLOAT_VAR, but getting only white color.