In OpenGL is there a way to get a list of all uniforms & attribs used by a shader program?

Question

I'd like to get a list of all the uniforms & attribs used by a shader program object. glGetAttribLocation() & glGetUniformLocation() can be used to map a string to a location, but what I would really like is the list of strings without having to parse the glsl code.

Note: In OpenGL 2.0 glGetObjectParameteriv() is replaced by glGetProgramiv(). And the enum is GL_ACTIVE_UNIFORMS & GL_ACTIVE_ATTRIBUTES.

Answer 1

Variables shared between both examples:

GLint i;
GLint count;

GLint size; // size of the variable
GLenum type; // type of the variable (float, vec3 or mat4, etc)

const GLsizei bufSize = 16; // maximum name length
GLchar name[bufSize]; // variable name in GLSL
GLsizei length; // name length

Attributes

glGetProgramiv(program, GL_ACTIVE_ATTRIBUTES, &count);
printf("Active Attributes: %d\n", count);

for (i = 0; i < count; i++)
{
    glGetActiveAttrib(program, (GLuint)i, bufSize, &length, &size, &type, name);

    printf("Attribute #%d Type: %u Name: %s\n", i, type, name);
}

Uniforms

glGetProgramiv(program, GL_ACTIVE_UNIFORMS, &count);
printf("Active Uniforms: %d\n", count);

for (i = 0; i < count; i++)
{
    glGetActiveUniform(program, (GLuint)i, bufSize, &length, &size, &type, name);

    printf("Uniform #%d Type: %u Name: %s\n", i, type, name);
}

OpenGL Documentation / Variable Types

The various macros representing variable types can be found in the docs. Such as GL_FLOAT, GL_FLOAT_VEC3, GL_FLOAT_MAT4, etc.

• glGetActiveAttrib
• glGetActiveUniform