InstanceBatch.h

#ifndef NTA_INSTANCEBATCH_H_INCLUDED
#define NTA_INSTANCEBATCH_H_INCLUDED
 
#include "nta/SpriteBatch.h"
 
namespace nta {
    struct InstancedGlyph {
        InstancedGlyph(GLuint texture) : count(1), tex(texture) {
            glGenVertexArrays(1, &vao);
        }
        GLuint gen_vbo() {
            vbos.push_back(0);
            glGenBuffers(1, &vbos.back());
            return vbos.back();
        }
 
        GLsizei count;
        GLuint tex;
        GLuint vao;
        std::vector<GLuint> vbos;
    };
    class InstanceBatch {
    private:
        std::vector<InstancedGlyph> m_glyphs;
    public:
        InstanceBatch() {}
        ~InstanceBatch() { begin(); }
        void begin();
        void end() const {}
        void reset() { begin(); }
        void add_glyph(crvec4 posRect, GLuint texture = 0, 
                       crvec4 uvRect = glm::vec4(0,0,1,1), 
                       crvec4 color = glm::vec4(1));
        void add_instance_data(const VertexAttrib* attribs, std::size_t num_attribs, 
                               void* data, GLsizeiptr size, GLuint divisor = 1);
        void render() const;
    };
}
 
#endif // NTA_INSTANCEBATCH_H_INCLUDED