#pragma once

#include <d3dx9.h>

extern IDirect3DDevice9* g_d3d_device;

class TerrainGrid
{
public:
	typedef float (TerrainGrid::*iso_surface_function)(const D3DXVECTOR3&);

	void Init( int StepsXZ, int StepsY, iso_surface_function pIsoSurface );
	void Render();

	float IsoSurfaceIsle(const D3DXVECTOR3& pos);
	float IsoSurfaceCave(const D3DXVECTOR3& pos);
	float IsoSurfaceCaveGround(const D3DXVECTOR3& pos);

private:

	typedef struct
	{
	   D3DXVECTOR3 p[3];
	} TRIANGLE;

	typedef struct
	{
	   D3DXVECTOR3 p[8];
	   float val[8];
	} GRIDCELL;

	float PerlinNoise_2D(float x, float y, float scale);
	D3DXVECTOR3 VertexInterp(float isolevel, D3DXVECTOR3 p1, D3DXVECTOR3 p2, float valp1, float valp2);
	int Polygonise(GRIDCELL grid, float isolevel, TRIANGLE* triangles);
	D3DXVECTOR3 GetNormal(D3DXVECTOR3 input, iso_surface_function pIsoSurface);
	
	D3DLOCKED_BOX noiseLock;
	int vertexCount;
	int indexCount;
	IDirect3DVertexDeclaration9* vertexDecl;
	IDirect3DIndexBuffer9* indexBuffer;
	IDirect3DVertexBuffer9* vertexBuffer;
};

struct TerrainVertex
{
	D3DXVECTOR3 pos;
	D3DXVECTOR3 normal;
	D3DXVECTOR2 tex;
	D3DCOLOR col;
};