terravisor/source/uniforms.cpp

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

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

    //IDs for the buffer objects holding the uniform block data
    GLuint sceneUbo = 0;
    GLuint lightUbo = 0;
    GLuint materialUbo = 0;
    GLuint geoUbo = 0;

    namespace UboBinding
    {
        //These values come from the binding value specified in the shader block layout
        int scene = 0;
        int light = 1;
        int material = 2;
        int geometry = 4;
    };

    //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::sceneUbo);
        glBindBuffer(GL_UNIFORM_BUFFER, sceneUbo);
        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, sceneUbo); //Associate this uniform buffer with the uniform block in the shader that has the same binding.

        glGenBuffers(1, &lightUbo);
        glBindBuffer(GL_UNIFORM_BUFFER, lightUbo);
        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, lightUbo); //Associate this uniform buffer with the uniform block in the shader that has the same binding.

        glGenBuffers(1, &materialUbo);
        glBindBuffer(GL_UNIFORM_BUFFER, materialUbo);
        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, materialUbo); //Associate this uniform buffer with the uniform block in the shader that has the same binding.

        glGenBuffers(1, &geoUbo);
        glBindBuffer(GL_UNIFORM_BUFFER, geoUbo);
        glBufferData(GL_UNIFORM_BUFFER, sizeof(GeoUniforms), &GeoData, GL_STREAM_DRAW); //Allocate memory for the buffer, but don't copy (since pointer is null).
        glBindBufferBase(GL_UNIFORM_BUFFER, UboBinding::geometry, geoUbo); //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, sceneUbo); //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

        glBindBuffer(GL_UNIFORM_BUFFER, geoUbo); //Bind the OpenGL UBO before we update the data.
        glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(GeoData), &GeoData); //Upload the new uniform values.
        glBindBuffer(GL_UNIFORM_BUFFER, 0); //unbind the ubo
    }
};