ClusterLodGenerator.h

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#pragma once

 
#include "Engine/Ecs/EcsData.h"
#include "Engine/Mesh/Vertex.h"
#include "Engine/Renderer/RenderData.h"
#include <vector>
 
namespace EngineCore
{

struct LodGenerationConfig
{
    size_t maxTrianglesPerCluster = 128;     
    float simplificationRatio = 0.5f;        
    float targetError = 0.01f;               
    size_t maxLodLevels = 6;                 
    size_t minTrianglesForLod = 256;         
};

class ClusterLodGenerator
{
public:
    static Ecs::LodHierarchyResult generate(
        const std::vector<Vertex>& vertices,
        const std::vector<uint32_t>& indices,
        const std::vector<meshopt_Meshlet>& baseMeshlets,
        const std::vector<uint32_t>& baseMeshletVertices,
        const std::vector<uint8_t>& baseMeshletTriangles,
        const LodGenerationConfig& config = {}
    );
 
private:
    struct LodLevelData
    {
        std::vector<Vertex> vertices;
        std::vector<uint32_t> indices;
        std::vector<meshopt_Meshlet> meshlets;
        std::vector<uint32_t> meshletVertices;
        std::vector<uint8_t> meshletTriangles;
        float error;  
    };
 
    static LodLevelData generateLodLevel(
        const std::vector<Vertex>& srcVertices,
        const std::vector<uint32_t>& srcIndices,
        size_t targetIndexCount,
        float targetError,
        size_t maxVerticesPerMeshlet,
        size_t maxTrianglesPerMeshlet
    );

    static glm::vec4 computeBoundingSphere(
        const std::vector<Vertex>& vertices,
        const std::vector<uint32_t>& indices
    );

    static glm::vec4 computeMeshletBoundingSphere(
        const std::vector<Vertex>& vertices,
        const meshopt_Meshlet& meshlet,
        const std::vector<uint32_t>& meshletVertices
    );
};
 
}  // namespace EngineCore