qzdoom/src/gl/dynlights/gl_lightbsp.h

#pragma once

#include "vectors.h"
#include <memory>

struct GPUNode
{
	GPUNode(const FVector2 &aabb_min, const FVector2 &aabb_max, int line_index) : aabb_left(aabb_min.X), aabb_top(aabb_min.Y), aabb_right(aabb_max.X), aabb_bottom(aabb_max.Y), left(-1), right(-1), line_index(line_index) { }
	GPUNode(const FVector2 &aabb_min, const FVector2 &aabb_max, int left, int right) : aabb_left(aabb_min.X), aabb_top(aabb_min.Y), aabb_right(aabb_max.X), aabb_bottom(aabb_max.Y), left(left), right(right), line_index(-1) { }

	float aabb_left, aabb_top;
	float aabb_right, aabb_bottom;
	int left;
	int right;
	int line_index;
	int padding;
};

struct GPULine
{
	float x, y;
	float dx, dy;
};

class Level2DShape
{
public:
	Level2DShape();

	TArray<GPUNode> nodes;
	TArray<GPULine> lines;
	int root;

	double RayTest(const DVector3 &ray_start, const DVector3 &ray_end);

private:
	bool OverlapRayAABB(const DVector2 &ray_start2d, const DVector2 &ray_end2d, const GPUNode &node);
	double IntersectRayLine(const DVector2 &ray_start, const DVector2 &ray_end, int line_index, const DVector2 &raydelta, double rayd, double raydist2);

	int Subdivide(int *lines, int num_lines, const FVector2 *centroids, int *work_buffer);
};

class FLightBSP
{
public:
	FLightBSP() { }
	~FLightBSP() { Clear(); }

	int GetNodesBuffer();
	int GetLinesBuffer();
	void Clear();

	bool ShadowTest(const DVector3 &light, const DVector3 &pos);

private:
	void UpdateBuffers();
	void GenerateBuffers();
	void UploadNodes();
	void UploadSegs();

	FLightBSP(const FLightBSP &) = delete;
	FLightBSP &operator=(FLightBSP &) = delete;

	int NodesBuffer = 0;
	int LinesBuffer = 0;
	int NumNodes = 0;
	int NumSegs = 0;

	std::unique_ptr<Level2DShape> Shape;
};