www.pudn.com > Terrain.rar > terrain.cpp
//////////////////////////////////////////////////////////////////////////////////////////////////
//
// File: terrain.cpp
//
// Author: Frank Luna (C) All Rights Reserved
//
// System: AMD Athlon 1800+ XP, 512 DDR, Geforce 3, Windows XP, MSVC++ 7.0
//
// Desc: Represents a 3D terrain.
//
//////////////////////////////////////////////////////////////////////////////////////////////////
#include "terrain.h"
#include
#include
const DWORD Terrain::TerrainVertex::FVF = D3DFVF_XYZ | D3DFVF_TEX1;
Terrain::Terrain(IDirect3DDevice9* device,
std::string heightmapFileName,
int numVertsPerRow,
int numVertsPerCol,
int cellSpacing,
float heightScale)
{
_device = device;
_numVertsPerRow = numVertsPerRow;
_numVertsPerCol = numVertsPerCol;
_cellSpacing = cellSpacing;
_numCellsPerRow = _numVertsPerRow - 1;
_numCellsPerCol = _numVertsPerCol - 1;
_width = _numCellsPerRow * _cellSpacing;
_depth = _numCellsPerCol * _cellSpacing;
_numVertices = _numVertsPerRow * _numVertsPerCol;
_numTriangles = _numCellsPerRow * _numCellsPerCol * 2;
_heightScale = heightScale;
// load heightmap
if( !readRawFile(heightmapFileName) )
{
::MessageBox(0, "readRawFile - FAILED", 0, 0);
::PostQuitMessage(0);
}
// scale heights
for(int i = 0; i < _heightmap.size(); i++)
_heightmap[i] *= heightScale;
// compute the vertices
if( !computeVertices() )
{
::MessageBox(0, "computeVertices - FAILED", 0, 0);
::PostQuitMessage(0);
}
// compute the indices
if( !computeIndices() )
{
::MessageBox(0, "computeIndices - FAILED", 0, 0);
::PostQuitMessage(0);
}
}
Terrain::~Terrain()
{
d3d::Release(_vb);
d3d::Release(_ib);
d3d::Release(_tex);
}
int Terrain::getHeightmapEntry(int row, int col)
{
return _heightmap[row * _numVertsPerRow + col];
}
void Terrain::setHeightmapEntry(int row, int col, int value)
{
_heightmap[row * _numVertsPerRow + col] = value;
}
bool Terrain::computeVertices()
{
HRESULT hr = 0;
hr = _device->CreateVertexBuffer(
_numVertices * sizeof(TerrainVertex),
D3DUSAGE_WRITEONLY,
TerrainVertex::FVF,
D3DPOOL_MANAGED,
&_vb,
0);
if(FAILED(hr))
return false;
// coordinates to start generating vertices at
int startX = -_width / 2;
int startZ = _depth / 2;
// coordinates to end generating vertices at
int endX = _width / 2;
int endZ = -_depth / 2;
// compute the increment size of the texture coordinates
// from one vertex to the next.
float uCoordIncrementSize = 1.0f / (float)_numCellsPerRow;
float vCoordIncrementSize = 1.0f / (float)_numCellsPerCol;
TerrainVertex* v = 0;
_vb->Lock(0, 0, (void**)&v, 0);
int i = 0;
for(int z = startZ; z >= endZ; z -= _cellSpacing)
{
int j = 0;
for(int x = startX; x <= endX; x += _cellSpacing)
{
// compute the correct index into the vertex buffer and heightmap
// based on where we are in the nested loop.
int index = i * _numVertsPerRow + j;
v[index] = TerrainVertex(
(float)x,
(float)_heightmap[index],
(float)z,
(float)j * uCoordIncrementSize,
(float)i * vCoordIncrementSize);
j++; // next column
}
i++; // next row
}
_vb->Unlock();
return true;
}
bool Terrain::computeIndices()
{
HRESULT hr = 0;
hr = _device->CreateIndexBuffer(
_numTriangles * 3 * sizeof(WORD), // 3 indices per triangle
D3DUSAGE_WRITEONLY,
D3DFMT_INDEX16,
D3DPOOL_MANAGED,
&_ib,
0);
if(FAILED(hr))
return false;
WORD* indices = 0;
_ib->Lock(0, 0, (void**)&indices, 0);
// index to start of a group of 6 indices that describe the
// two triangles that make up a quad
int baseIndex = 0;
// loop through and compute the triangles of each quad
for(int i = 0; i < _numCellsPerCol; i++)
{
for(int j = 0; j < _numCellsPerRow; j++)
{
indices[baseIndex] = i * _numVertsPerRow + j;
indices[baseIndex + 1] = i * _numVertsPerRow + j + 1;
indices[baseIndex + 2] = (i+1) * _numVertsPerRow + j;
indices[baseIndex + 3] = (i+1) * _numVertsPerRow + j;
indices[baseIndex + 4] = i * _numVertsPerRow + j + 1;
indices[baseIndex + 5] = (i+1) * _numVertsPerRow + j + 1;
// next quad
baseIndex += 6;
}
}
_ib->Unlock();
return true;
}
bool Terrain::loadTexture(std::string fileName)
{
HRESULT hr = 0;
hr = D3DXCreateTextureFromFile(
_device,
fileName.c_str(),
&_tex);
if(FAILED(hr))
return false;
return true;
}
bool Terrain::genTexture(D3DXVECTOR3* directionToLight)
{
// Method fills the top surface of a texture procedurally. Then
// lights the top surface. Finally, it fills the other mipmap
// surfaces based on the top surface data using D3DXFilterTexture.
HRESULT hr = 0;
// texel for each quad cell
int texWidth = _numCellsPerRow;
int texHeight = _numCellsPerCol;
// create an empty texture
hr = D3DXCreateTexture(
_device,
texWidth, texHeight,
0, // create a complete mipmap chain
0, // usage
D3DFMT_X8R8G8B8,// 32 bit XRGB format
D3DPOOL_MANAGED, &_tex);
if(FAILED(hr))
return false;
D3DSURFACE_DESC textureDesc;
_tex->GetLevelDesc(0 /*level*/, &textureDesc);
// make sure we got the requested format because our code
// that fills the texture is hard coded to a 32 bit pixel depth.
if( textureDesc.Format != D3DFMT_X8R8G8B8 )
return false;
D3DLOCKED_RECT lockedRect;
_tex->LockRect(0/*lock top surface*/, &lockedRect,
0 /* lock entire tex*/, 0/*flags*/);
DWORD* imageData = (DWORD*)lockedRect.pBits;
for(int i = 0; i < texHeight; i++)
{
for(int j = 0; j < texWidth; j++)
{
D3DXCOLOR c;
// get height of upper left vertex of quad.
float height = (float)getHeightmapEntry(i, j) / _heightScale;
if( (height) < 42.5f ) c = d3d::BEACH_SAND;
else if( (height) < 85.0f ) c = d3d::LIGHT_YELLOW_GREEN;
else if( (height) < 127.5f ) c = d3d::PUREGREEN;
else if( (height) < 170.0f ) c = d3d::DARK_YELLOW_GREEN;
else if( (height) < 212.5f ) c = d3d::DARKBROWN;
else c = d3d::WHITE;
// fill locked data, note we divide the pitch by four because the
// pitch is given in bytes and there are 4 bytes per DWORD.
imageData[i * lockedRect.Pitch / 4 + j] = (D3DCOLOR)c;
}
}
_tex->UnlockRect(0);
if(!lightTerrain(directionToLight))
{
::MessageBox(0, "lightTerrain() - FAILED", 0, 0);
return false;
}
hr = D3DXFilterTexture(
_tex,
0, // default palette
0, // use top level as source level
D3DX_DEFAULT); // default filter
if(FAILED(hr))
{
::MessageBox(0, "D3DXFilterTexture() - FAILED", 0, 0);
return false;
}
return true;
}
bool Terrain::lightTerrain(D3DXVECTOR3* directionToLight)
{
HRESULT hr = 0;
D3DSURFACE_DESC textureDesc;
_tex->GetLevelDesc(0 /*level*/, &textureDesc);
// make sure we got the requested format because our code that fills the
// texture is hard coded to a 32 bit pixel depth.
if( textureDesc.Format != D3DFMT_X8R8G8B8 )
return false;
D3DLOCKED_RECT lockedRect;
_tex->LockRect(
0, // lock top surface level in mipmap chain
&lockedRect,// pointer to receive locked data
0, // lock entire texture image
0); // no lock flags specified
DWORD* imageData = (DWORD*)lockedRect.pBits;
for(int i = 0; i < textureDesc.Height; i++)
{
for(int j = 0; j < textureDesc.Width; j++)
{
// index into texture, note we use the pitch and divide by
// four since the pitch is given in bytes and there are
// 4 bytes per DWORD.
int index = i * lockedRect.Pitch / 4 + j;
// get current color of quad
D3DXCOLOR c( imageData[index] );
// shade current quad
c *= computeShade(i, j, directionToLight);;
// save shaded color
imageData[index] = (D3DCOLOR)c;
}
}
_tex->UnlockRect(0);
return true;
}
float Terrain::computeShade(int cellRow, int cellCol, D3DXVECTOR3* directionToLight)
{
// get heights of three vertices on the quad
float heightA = getHeightmapEntry(cellRow, cellCol);
float heightB = getHeightmapEntry(cellRow, cellCol+1);
float heightC = getHeightmapEntry(cellRow+1, cellCol);
// build two vectors on the quad
D3DXVECTOR3 u(_cellSpacing, heightB - heightA, 0.0f);
D3DXVECTOR3 v(0.0f, heightC - heightA, -_cellSpacing);
// find the normal by taking the cross product of two
// vectors on the quad.
D3DXVECTOR3 n;
D3DXVec3Cross(&n, &u, &v);
D3DXVec3Normalize(&n, &n);
float cosine = D3DXVec3Dot(&n, directionToLight);
if(cosine < 0.0f)
cosine = 0.0f;
return cosine;
}
bool Terrain::readRawFile(std::string fileName)
{
// Restriction: RAW file dimensions must be >= to the
// dimensions of the terrain. That is a 128x128 RAW file
// can only be used with a terrain constructed with at most
// 128x128 vertices.
// A height for each vertex
std::vector in( _numVertices );
std::ifstream inFile(fileName.c_str(), std::ios_base::binary);
if( inFile == 0 )
return false;
inFile.read(
(char*)&in[0], // buffer
in.size());// number of bytes to read into buffer
inFile.close();
// copy BYTE vector to int vector
_heightmap.resize( _numVertices );
for(int i = 0; i < in.size(); i++)
_heightmap[i] = in[i];
return true;
}
float Terrain::getHeight(float x, float z)
{
// Translate on xz-plane by the transformation that takes
// the terrain START point to the origin.
x = ((float)_width / 2.0f) + x;
z = ((float)_depth / 2.0f) - z;
// Scale down by the transformation that makes the
// cellspacing equal to one. This is given by
// 1 / cellspacing since; cellspacing * 1 / cellspacing = 1.
x /= (float)_cellSpacing;
z /= (float)_cellSpacing;
// From now on, we will interpret our positive z-axis as
// going in the 'down' direction, rather than the 'up' direction.
// This allows to extract the row and column simply by 'flooring'
// x and z:
float col = ::floorf(x);
float row = ::floorf(z);
// get the heights of the quad we're in:
//
// A B
// *---*
// | / |
// *---*
// C D
float A = getHeightmapEntry(row, col);
float B = getHeightmapEntry(row, col+1);
float C = getHeightmapEntry(row+1, col);
float D = getHeightmapEntry(row+1, col+1);
//
// Find the triangle we are in:
//
// Translate by the transformation that takes the upper-left
// corner of the cell we are in to the origin. Recall that our
// cellspacing was nomalized to 1. Thus we have a unit square
// at the origin of our +x -> 'right' and +z -> 'down' system.
float dx = x - col;
float dz = z - row;
// Note the below compuations of u and v are unneccessary, we really
// only need the height, but we compute the entire vector to emphasis
// the books discussion.
float height = 0.0f;
if(dz < 1.0f - dx) // upper triangle ABC
{
float uy = B - A; // A->B
float vy = C - A; // A->C
// Linearly interpolate on each vector. The height is the vertex
// height the vectors u and v originate from {A}, plus the heights
// found by interpolating on each vector u and v.
height = A + d3d::Lerp(0.0f, uy, dx) + d3d::Lerp(0.0f, vy, dz);
}
else // lower triangle DCB
{
float uy = C - D; // D->C
float vy = B - D; // D->B
// Linearly interpolate on each vector. The height is the vertex
// height the vectors u and v originate from {D}, plus the heights
// found by interpolating on each vector u and v.
height = D + d3d::Lerp(0.0f, uy, 1.0f - dx) + d3d::Lerp(0.0f, vy, 1.0f - dz);
}
return height;
}
bool Terrain::draw(D3DXMATRIX* world, bool drawTris)
{
HRESULT hr = 0;
if( _device )
{
_device->SetTransform(D3DTS_WORLD, world);
_device->SetStreamSource(0, _vb, 0, sizeof(TerrainVertex));
_device->SetFVF(TerrainVertex::FVF);
_device->SetIndices(_ib);
_device->SetTexture(0, _tex);
// turn off lighting since we're lighting it ourselves
_device->SetRenderState(D3DRS_LIGHTING, false);
hr =_device->DrawIndexedPrimitive(
D3DPT_TRIANGLELIST,
0,
0,
_numVertices,
0,
_numTriangles);
_device->SetRenderState(D3DRS_LIGHTING, true);
if( drawTris )
{
_device->SetRenderState(D3DRS_FILLMODE, D3DFILL_WIREFRAME);
hr =_device->DrawIndexedPrimitive(
D3DPT_TRIANGLELIST,
0,
0,
_numVertices,
0,
_numTriangles);
_device->SetRenderState(D3DRS_FILLMODE, D3DFILL_SOLID);
}
if(FAILED(hr))
return false;
}
return true;
}