Mesh.hpp

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#pragma once
#include <Native/Filesystem.hpp>
#include <RHICore/Common.hpp>
#include <Core/Core.hpp>
#include <Math/Math.hpp>
 
namespace ModelViewer
{
    using namespace Foundation;
    using namespace Math;
    using namespace Core;
    using MeshIndex = uint32_t; // 32-bit index
    struct MeshVertex
    {
        vec3 pos;
        vec3 normal;
        vec3 tangent;
        vec3 bitangent;
        vec2 uv;
    };
#pragma pack(push, 1)
    struct MeshVertexCompact {
        uint16_t px, py, pz; // quantized fp16
        uint16_t tp;         // tangent [octa 8+8]
        uint32_t np;         // normal packed [snorm octa 15+15, bitangent sign 2]
        uint16_t u, v;       // UV coords fp16
        static MeshVertexCompact Pack(vec3 pos, vec3 normal, vec3 tangent, vec3 bitangent, vec2 uv);
        static MeshVertexCompact Pack(MeshVertex data)
        {
            return Pack(data.pos, data.normal, data.tangent, data.bitangent, data.uv);
        }
    };
    static_assert(sizeof(MeshVertexCompact) == 16);
    struct MeshMeshlet // same layout as meshopt_Meshlet
    {
        /* offsets within meshlet_vertices and meshlet_triangles arrays with meshlet data */
        uint32_t vertexOffset; // in vertices
        uint32_t triangleOffset; // in indices (3*triangles)
        /* number of vertices and triangles used in the meshlet; data is stored in consecutive range defined by offset and count */
        uint32_t vertexCount;
        uint32_t triangleCount;
        /* bounds */
        float4 sphereCenterRadius; // (x,y,z,r)
        float4 coneAxisAngle; // (x,y,z,cos(half solid angle))
        float3 coneApex;
    };
    static_assert(sizeof(MeshMeshlet) == 60);
#pragma pack(pop)
    using MeshMicroIndex = uint8_t; // 8-bit index into meshlet vertex array
    constexpr uint32_t kMeshletMaxVertices = 64;  // max vertices per meshlet
    constexpr uint32_t kMeshletMaxTriangles = 96; // max triangles per meshlet (indices=3*triangles)
    void meshBuildMeshlets(Vector<MeshMeshlet>& outMeshlet, Vector<MeshIndex>& outMeshletVertices, Vector<MeshMicroIndex>& outMeshletTriangles, Span<const MeshVertex> vertices, Span<const MeshIndex> indices);
    float meshGenerateLod(Vector<MeshIndex>& outIndices, Span<const MeshVertex> vertices, Span<const MeshIndex> indices, const float lodScale);
    void meshLoadObjFile(Vector<MeshVertex>& outVertex, Vector<MeshIndex>& outIndex, const Native::Path& path);
}