Example/Uniform Location Query Old

Querying and using uniform locations, under the old introspection API.

Vertex shader code:

...
uniform vec3 someVector;
uniform mat4 someMatrix;
...
// Code must use these uniforms to be active.

C++ code:

GLuint program = // Compile and link program.
GLint someVectorLoc = glGetUniformLocation(program, "someVector");
assert(someVectorLoc != -1); // If fails, then the uniform is inactive.
GLint someMatrixLoc = glGetUniformLocation(program, "someMatrix");
assert(someMatrixLoc != -1); // If fails, then the uniform is inactive.
...
glUseProgram(program);
glUniform3f(someVectorLoc, 3.0f, 3.0f, 4.0f);
GLfloat matrix[16];
// Fill `matrix` with data. Non-transposed matrix data.
glUniformMatrix4fv(someMatrixLoc, 1, GL_FALSE, matrix);