terravisor/source/Uniforms.cpp

#include "Uniforms.h"
#include <GL/glew.h>

namespace Uniforms
{
    SceneUniforms SceneData;
    LightUniforms LightData;
    MaterialUniforms MaterialData;

    //IDs for the buffer objects holding the uniform block data
    GLuint scene_ubo = -1;
    GLuint light_ubo = -1;
    GLuint material_ubo = -1;

    namespace UboBinding
    {
        //These values come from the binding value specified in the shader block layout
        int scene = 0;
        int light = 1;
        int material = 2;
    };

    //Locations for the uniforms which are not in uniform blocks
    namespace UniformLocs
    {
        int M = 0; //model matrix
        int time = 1;
    };

    void Init()
    {
        //Create and initialize uniform buffers
        glGenBuffers(1, &Uniforms::scene_ubo);
        glBindBuffer(GL_UNIFORM_BUFFER, scene_ubo);
        glBufferData(GL_UNIFORM_BUFFER, sizeof(SceneUniforms), nullptr, GL_STREAM_DRAW); //Allocate memory for the buffer, but don't copy (since pointer is null).
        glBindBufferBase(GL_UNIFORM_BUFFER, UboBinding::scene, scene_ubo); //Associate this uniform buffer with the uniform block in the shader that has the same binding.

        glGenBuffers(1, &light_ubo);
        glBindBuffer(GL_UNIFORM_BUFFER, light_ubo);
        glBufferData(GL_UNIFORM_BUFFER, sizeof(LightUniforms), &LightData, GL_STREAM_DRAW); //Allocate memory for the buffer, but don't copy (since pointer is null).
        glBindBufferBase(GL_UNIFORM_BUFFER, UboBinding::light, light_ubo); //Associate this uniform buffer with the uniform block in the shader that has the same binding.

        glGenBuffers(1, &material_ubo);
        glBindBuffer(GL_UNIFORM_BUFFER, material_ubo);
        glBufferData(GL_UNIFORM_BUFFER, sizeof(MaterialUniforms), &MaterialData, GL_STREAM_DRAW); //Allocate memory for the buffer, but don't copy (since pointer is null).
        glBindBufferBase(GL_UNIFORM_BUFFER, UboBinding::material, material_ubo); //Associate this uniform buffer with the uniform block in the shader that has the same binding.

        glBindBuffer(GL_UNIFORM_BUFFER, 0);
    }

    void BufferSceneData()
    {
        glBindBuffer(GL_UNIFORM_BUFFER, scene_ubo); //Bind the OpenGL UBO before we update the data.
        glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(SceneData), &SceneData); //Upload the new uniform values.
        glBindBuffer(GL_UNIFORM_BUFFER, 0); //unbind the ubo
    }
};