heightfield.h File Reference

Go to the source code of this file.

Functions
void	initHeightField (int W, int H, const char *file)
	Initialize the height field.
void	drawHeightField (float x, float y, int w, int h)
	Draw the height field.
float	gethf (int, int)
	Get value of the height field at certain coordinate.

---

Function Documentation

void drawHeightField (  float  x, float  y, int  w, int  h )

Draw the height field. The field is placed in the XY plane centered in (0,0,0). The height field position (x,y) lies in the origin, and w x h tiles around this position are drawn. Each tile covers 1 square unit in OpenGL coordinates. Definition at line 363 of file heightfield.cpp. References averageHeight(), _S_VertexData::bShadow, _S_VertexData::bWater, drawMultipassQuad(), drawWaterQuads(), g_bBlending, gethfVertexData(), hftexture(), initGLState(), _S_VertexData::nTex, streamVertex(), TEX_N, texture(), TEXTURE, _S_VertexData::x, _S_WaterQuad::x, _S_WaterQuad::xp, _S_WaterQuad::y, _S_WaterQuad::yp, and _S_VertexData::z. Referenced by renderScene(). { // List of the water quads (rendered after field) vector<_S_WaterQuad> water; initGLState(); int xi = int(x); int yi = int(y); for (int xc=xi-w; xc <= xi+w; xc++ ) { TEXTURE nCurrentTexture = TEX_N; _S_VertexData v1, v2; gethfVertexData( x,y, xc+1, yi-h, v1 ); gethfVertexData( x,y, xc, yi-h, v2 ); for ( int yc=yi-h; yc <= yi+h; yc++ ) { _S_VertexData v3, v4; gethfVertexData( x,y, xc, yc+1, v3 ); gethfVertexData( x,y, xc+1, yc+1, v4 ); // Get correct textures for all four vertices of the next quad TEXTURE t1 = v1.nTex; TEXTURE t2 = v2.nTex; TEXTURE t3 = v3.nTex; TEXTURE t4 = v4.nTex; // Check if all are equal bool bAllEqual = false; if (t1==t2 && t2==t3 && t3==t4) { bAllEqual = true; } // Check if shadow quad bool bShadow = false; if (v1.bShadow || v2.bShadow || v3.bShadow || v4.bShadow) { bShadow = true; } bool bWater = false; if (v1.bWater || v2.bWater || v3.bWater || v4.bWater) { bWater = true; } if (bAllEqual && t1==nCurrentTexture && !bShadow && !bWater) { // Continue current triangle strip assert( t1 != TEX_N ); streamVertex( v1 ); streamVertex( v2 ); } else { // The current texture changes. Stop the triangle strip, // if one is currently active. if ( nCurrentTexture != TEX_N ) { streamVertex( v1 ); streamVertex( v2 ); nCurrentTexture = TEX_N; glEnd(); } if (bAllEqual && !bShadow && !bWater) { // Only one pass is required. Start a new active // triangle strip. glBindTexture( GL_TEXTURE_2D, texture(t1) ); glBegin( GL_TRIANGLE_STRIP ); nCurrentTexture = t1; streamVertex( v1 ); streamVertex( v2 ); } else { if ( g_bBlending && !bAllEqual ) { // Draw the current quad using multiple passes. // Get coordinates for next vertices in the strip drawMultipassQuad( v1,v2,v3,v4 ); } else { // Just use the texture for the average height TEXTURE tex = hftexture( averageHeight( xc,yc )); glBindTexture( GL_TEXTURE_2D, texture(tex) ); glBegin( GL_QUADS ); streamVertex( v1 ); streamVertex( v2 ); streamVertex( v3 ); streamVertex( v4 ); glEnd(); } if (bWater) { _S_WaterQuad W; W.x = xc; W.y = yc; W.xp = v2.x; W.yp = v2.z; water.push_back( W ); } } } v1 = v4; v2 = v3; } glEnd(); } glDisable( GL_TEXTURE_2D ); drawWaterQuads( water ); glEnable( GL_LIGHTING ); }

float gethf (  int  , int  )

Get value of the height field at certain coordinate. Definition at line 52 of file heightfield.cpp. References g_H, g_hf, and g_W. { // Not exactly as in the previous assignment, but looks // better than modulo. x = abs(x); y=abs(y); // while (x<0) x += g_hfW; // while (y<0) y += g_hfH; // Tile HF over full plane return g_hf[ (x%g_W) + (y%g_H)*g_W ]; }

void initHeightField (  int  W, int  H, const char *  file )

Initialize the height field. The field data is loaded as W*H continuous raw floats from the file. Definition at line 124 of file heightfield.cpp. References computeNormal(), g_cellsize, g_fHeightScale, g_H, g_hf, g_hfData, g_strResourceDir, g_texcoord, g_tpt, g_W, gethf(), hftexture(), _S_VertexData::nTex, _S_VertexData::nx, _S_VertexData::ny, _S_VertexData::nz, _S_VertexData::tx, _S_VertexData::ty, _S_VertexData::x, _S_VertexData::y, and _S_VertexData::z. Referenced by initGL(). { // Validate params assert( W>0 && W*H > 0 ); // Clear old data if (g_hf != NULL) { delete[] g_hf; } if (g_hfData != NULL) { delete[] g_hfData; } // Init new data g_W = W; g_H = H; g_hf = new float[W*H]; g_hfData = new _S_VertexData[W*H]; // Read data from file if (filename != NULL) { int L = strlen( filename ) + strlen( g_strResourceDir ); char fn[L+1]; strcpy( fn, g_strResourceDir ); strcat( fn, filename ); FILE *file = fopen( fn, "rb" ); assert( file != NULL ); int n; if ( (n=fread( g_hf, sizeof(float), W*H, file )) != W*H) { printf( "Error loading height field, only %i floats read.", n ); } else { printf( "read %i floats ... ", n ); } } // Init texture coords for ( int i=0; i<=g_tpt; i++) { g_texcoord[i] = float(i) / float(g_tpt); } for ( int i=0; i<g_tpt; i++) { g_texcoord[i + g_tpt] = 1.0f - float(i) / float(g_tpt); } // Init height field for (int x=0; x<g_W; x++) { for (int y=0; y<g_H; y++) { g_hf[ x+y*g_W ] *= g_fHeightScale; } } // Init per vertex height field data for (int x=0; x<g_W; x++) { for (int y=0; y<g_H; y++) { _S_VertexData &V = g_hfData[ x+y*g_W ]; V.x = x * g_cellsize; V.y = gethf( x,y ); V.z = y * g_cellsize; computeNormal( x,y, V.nx, V.ny, V.nz ); V.tx = g_texcoord[ abs(x) % (2*g_tpt) ]; V.ty = g_texcoord[ abs(y) % (2*g_tpt) ]; V.nTex = hftexture( V.y ); } } }

---