龙书9 chapter13 14 地形绘制的过程和terrain类的实现、 粒子系统入门笔记

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);

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;//超越0-255的限制
	std::vector<int> _heightmap;//vertex Y
	// helper methods
	bool  readRawFile(std::string fileName);//读取灰度图
	bool  computeVertices();
	bool  computeIndices();
	bool  lightTerrain(D3DXVECTOR3* directionToLight);
	float computeShade(int cellRow, int cellCol, D3DXVECTOR3* directionToLight);//计算单位网格中纹理在light方向光下的明暗程度

	struct TerrainVertex//内嵌类 只与terrain使用
	{
		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;
	};
};