How can I find a list of all the uniforms in OpenGL es 2.0 vertex shader pro

Question

I'm trying to learn how to program vertex shaders. In Apple's sample project they have a line to set a

glUniform1f(uniforms[UNIFORM_TRANSLATE], (Glfloat)transY);

Then this value is used in

// value passt in f
// glUniform1f(uniforms[UNIFORM_TRANSLATE](Glfloat)transY);
uniform float translate;

void main()
{
    gl_Position.y+=sin( translate);
…

I was unable to find a list of all uniforms of all the uniforms.

Does any one know where I can find a list of all the uniforms and a good book or tutorial on learning how to program vertex shaders.

Answer 1

Uniform parameter is a data passed to GL shader, which doesn't change during the draw call.

You can query a linked GLSL program for a list of active uniforms with the following code:

int total = -1;
glGetProgramiv( program_id, GL_ACTIVE_UNIFORMS, &total ); 
for(int i=0; i<total; ++i)  {
    int name_len=-1, num=-1;
    GLenum type = GL_ZERO;
    char name[100];
    glGetActiveUniform( program_id, GLuint(i), sizeof(name)-1,
        &name_len, &num, &type, name );
    name[name_len] = 0;
    GLuint location = glGetUniformLocation( program_id, name );
}

This code retrieves a number of active uniforms and iterates though them, extracting name, type, number of values and uniform locations.