heightfield.cpp File Reference

#include <GL/gl.h>
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include "heightfield.h"
#include "config.h"
#include "texture.h"

Go to the source code of this file.

Functions
void	initHeightField ()
	Initialize the height field.
float	gethf (int x, int y)
	Get value of the height field at certain coordinate.
void	setDiffuseMaterialColor (const float *mc)
void	renderGroundQuad (float w, float h)
void	drawHeightField (float x, float y, int w, int h)
	Draw the height field.
Variables
float *	g_hf = NULL

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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). A transformation is set up so that the height field position (x,y) is moved into the origin, and w x h tiles around this position are drawn. Each tile covers g_cellsize square units in OpenGL coordinates. Definition at line 109 of file heightfield.cpp. References renderGroundQuad(), TEX_ROCK, TEX_SNOW, and texture(). Referenced by renderScene(). { // Automatic normals do not work correctly for a height field, // because there is no interaction between two adjacent strips. // In the solution, you will have to compute the normals of // the field yourself. glEnable( GL_AUTO_NORMAL ); // Enable the grass texture glBindTexture( GL_TEXTURE_2D, texture( TEX_SNOW )); glEnable( GL_TEXTURE_2D ); // Render ground once renderGroundQuad( w,h ); // Allow equal depth buffer values, otherwise the quad is not rendered // a second time glDepthFunc( GL_LEQUAL ); // Switch to the second texture glDisable( GL_TEXTURE_2D ); glBindTexture( GL_TEXTURE_2D, texture( TEX_ROCK )); glEnable( GL_TEXTURE_2D ); // Setup blending so that it blends with the framebuffer and the new // geometry using the value in the alpha channel as a weight glBlendEquation( GL_ADD ); glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ); // Switch on alpha blending, and render ground again glEnable( GL_BLEND ); renderGroundQuad( w,h ); // Reset rendering state glDepthFunc( GL_LESS ); glDisable( GL_BLEND ); glDisable( GL_TEXTURE_2D ); glDisable( GL_AUTO_NORMAL ); }

float gethf (  int  x, int  y )

Get value of the height field at certain coordinate. Definition at line 49 of file heightfield.cpp. References g_hf, g_hfH, and g_hfW. Referenced by renderGroundQuad(). { assert( x>=0 && x<g_hfW ); assert( y>=0 && y<g_hfH ); return g_hf[ x + y*g_hfW ]; }

void initHeightField (   )

Initialize the height field. The field data is loaded as g_hfW*g_hfH continuous raw floats from the file. Definition at line 15 of file heightfield.cpp. References g_hf, g_hfH, g_hfW, g_strHeightFieldFile, and g_strResourceDir. Referenced by initGL(). { // Validate params int W = g_hfW; int H = g_hfH; assert( W>0 && W*H > 0 ); // Clear old data if (g_hf != NULL) { delete[] g_hf; } // Init new data g_hf = new float[W*H]; memset( g_hf,0, W*H*sizeof(float) ); // Read data from file char filename[500]; strcpy( filename, g_strResourceDir ); strcat( filename, g_strHeightFieldFile ); printf( "Reading height field %s\n", filename ); FILE *file = fopen( filename, "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 ); } }

void renderGroundQuad (  float  w, float  h )

Definition at line 69 of file heightfield.cpp. References gethf(), and setDiffuseMaterialColor(). Referenced by drawHeightField(). { static const float transparent_alpha[4] = {1,1,1,0}; static const float opaque_alpha[4] = {1,1,1,1}; glBegin( GL_QUADS ); // At negative w, make transparent if alpha blending is on setDiffuseMaterialColor( transparent_alpha ); // Texture coordinates have to be defined before the vertex glTexCoord2f( 0,1 ); glVertex3f( -w, h, gethf(0,2) ); glTexCoord2f( 0,0 ); glVertex3f( -w,-h, gethf(0,0) ); // At positive w, make opaque if alpha blending is on setDiffuseMaterialColor( opaque_alpha ); glTexCoord2f( 1, 0 ); glVertex3f( w,-h, gethf(2,0) ); glTexCoord2f( 1, 1 ); glVertex3f( w, h, gethf(2,2) ); glEnd(); }

void setDiffuseMaterialColor (  const float *  mc  )

Definition at line 57 of file heightfield.cpp. References colorNone. Referenced by renderGroundQuad(). { glMaterialfv(GL_FRONT, GL_DIFFUSE, mc ); glMaterialfv(GL_FRONT, GL_AMBIENT, mc ); glMaterialfv(GL_FRONT, GL_SPECULAR, colorNone ); glColor4fv(mc); }

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Variable Documentation

float* g_hf = NULL [static]

Definition at line 12 of file heightfield.cpp. Referenced by gethf(), and initHeightField().

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