#pragma once
#include "hd2d/GL.h"

#include <glm/glm.hpp>
#include <vector>

namespace hd2d {

class ModelBatch;

// Baked contact ambient occlusion on the ground under 3D scenery: a dark,
// tight core at a tree trunk / bush / rock base plus a wide, soft canopy
// shadow under tall models. Sampled by terrain, sprite and model shaders, so
// grass tufts and bushes growing at a tree's foot darken too. Rebuild after
// moving instances.
class GroundOcclusion {
public:
    GroundOcclusion() = default;
    GroundOcclusion(const GroundOcclusion&) = delete;
    GroundOcclusion& operator=(const GroundOcclusion&) = delete;
    ~GroundOcclusion();

    // Covers the rectangle [min, max] (world xz). Uses every batch whose
    // `groundOcclusion` strength is > 0.
    void build(glm::vec2 min, glm::vec2 max, const std::vector<ModelBatch*>& batches, int texelsPerUnit = 8);

    GLuint texture() const { return tex_; }
    glm::vec4 rect() const { return rect_; }  // matches uGroundAO in common.glsl

private:
    GLuint tex_ = 0;
    glm::vec4 rect_{0.0f};
};

}  // namespace hd2d