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Terrain

Terrain. Basic Terrain Rendering. 산이나 계곡등의 지형을 나타내는 방식 텍스쳐를 추가하면 해변이나 풀덮인 언덕 , 눈덮힌 산 등을 표현할 수도 있다 . 전체 지형을 다 그리는 것은 낭비이며 보이는 부분만 그리고 (View Frustum Culling), 멀리 있는 물체는 덜 세밀하게 그려야 (LOD:Level of Detail) 속도가 향상된다. Terrain Representation. Height Map

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Terrain

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  1. Terrain

  2. Basic Terrain Rendering • 산이나 계곡등의 지형을 나타내는 방식 • 텍스쳐를 추가하면 해변이나 풀덮인 언덕, 눈덮힌 산 등을 표현할 수도 있다. • 전체 지형을 다 그리는 것은 낭비이며 보이는 부분만 그리고(View Frustum Culling), 멀리 있는 물체는 덜 세밀하게 그려야 (LOD:Level of Detail)속도가 향상된다.

  3. Terrain Representation • Height Map • 사각형의 지역내 각각의 점에 높이 값이 저장되어 있는 map (2차원 이미지와 비슷한 개념) • Height Map을 Geometry로 변환 (0,0) (1,0) • 높이 좌표는 height map 참조 (0,1) (1,1)

  4. Terrain LOD • Cracks, T-junctions • How do we solve this?

  5. Terrain LOD • Subdivide the terrain such that this is easier or done for free • Quadtrees , Bintrees

  6. Quadtree • Each quad is actually two triangles • Still have cracks and T-junctions • Easy to implement

  7. Binary Triangle Tree (bintree) • Cracks and T-junctions are solved! • Any two triangles differ by no more than one resolution level • A little harder to implement • Forced Splitting

  8. Error Estimation/Control τ = 2 pixels 79,382 triangles τ = 4 pixels 25,100 triangles

  9. 지형위를 걷기 • 현재 서있는 지점의 높이(y 좌표)에 따라 카메라의 높이를 조절한다. • 카메라 위치 즉 x와 z축 좌표를 이용하여 현재의 셀(삼각형)을 찾아내야 한다. • 그 후 x,z좌표값에서 해당되는 삼각형의 높이값을 계산한다. (0,0) (1,0) (0,1) (1,1)

  10. private: IDirect3DDevice9* _device; IDirect3DTexture9* _tex; IDirect3DVertexBuffer9* _vb; IDirect3DIndexBuffer9* _ib; int _numVertsPerRow; int _numVertsPerCol; int _cellSpacing; int _numCellsPerRow; int _numCellsPerCol; int _width; int _depth; int _numVertices; int _numTriangles; float _heightScale; std::vector<int> _heightmap; // helper methods bool readRawFile(std::string fileName); bool computeVertices(); bool computeIndices(); bool lightTerrain(D3DXVECTOR3* directionToLight); float computeShade(int cellRow, int cellCol, D3DXVECTOR3* directionToLight); struct TerrainVertex { TerrainVertex(){} TerrainVertex(float x,float y,float z,float u,float v) { _x = x; _y = y; _z = z; _u = u; _v = v; } float _x, _y, _z; float _u, _v; static const DWORD FVF; }; }; class Terrain { public: Terrain( IDirect3DDevice9* device, std::string heightmapFileName, int numVertsPerRow, int numVertsPerCol, int cellSpacing, // space between cells float heightScale); ~Terrain(); int getHeightmapEntry(int row, int col); void setHeightmapEntry(int row, int col, int value); float getHeight(float x, float z); bool loadTexture(std::string fileName); bool genTexture(D3DXVECTOR3* directionToLight); bool draw(D3DXMATRIX* world, bool drawTris);

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