BaseRenderer.h

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#ifndef CHRYSALIS_BASERENDERER_H
#define CHRYSALIS_BASERENDERER_H
 
#include <glad/gl.h>
 
#include "BaseRendererData.h"
 
namespace Chrysalis {
    template<typename D>
    requires requires {
        []<typename V>(BaseRendererData<V>*) -> auto {}(static_cast<D*>(nullptr));
    }
    class BaseRenderer {
        using V = decltype([]<typename V>(BaseRendererData<V>*) -> V {}(static_cast<D*>(nullptr)));
    protected:
        explicit BaseRenderer(D* data): data_(data) {}
        virtual ~BaseRenderer() {
            delete data_;
            if (vbo_ != 0) glDeleteBuffers(1, &vbo_);
            if (vao_ != 0) glDeleteVertexArrays(1, &vao_);
        }
 
    public:
        void upload() {
            if (!data_->shouldUpload()) return;
            glBindVertexArray(vao_);
            glBindBuffer(GL_ARRAY_BUFFER, vbo_);
            glBufferData(GL_ARRAY_BUFFER, data_->size() * sizeof(V), data_->vbo().data(), GL_DYNAMIC_DRAW);
            glBindBuffer(GL_ARRAY_BUFFER, 0);
            glBindVertexArray(0);
        }
 
        virtual void initialize() {
            glGenVertexArrays(1, &vao_);
            glBindVertexArray(vao_);
 
            glGenBuffers(1, &vbo_);
            glBindBuffer(GL_ARRAY_BUFFER, vbo_);
 
            const auto layout = V::layout();
            for (GLuint i = 0; i < layout.size(); i++) {
                const auto& [count, offset] = layout[i];
                glEnableVertexAttribArray(i);
                glVertexAttribPointer(i, count, GL_FLOAT, GL_FALSE, sizeof(V), offset);
            }
 
            upload();
        }
 
        void render() {
            glBindVertexArray(vao_);
            draw();
            glBindVertexArray(0);
        }
 
        virtual void draw() = 0;
    protected:
        D* data_;
    private:
        GLuint vbo_ = 0;
        GLuint vao_ = 0;
    };
}
 
#endif //CHRYSALIS_BASERENDERER_H