glants_mech/win32/glAntsV05/los.cpp

   1 //
   2 // los.cpp
   3 //
   4 // - line of sight algorithm for the fire ant AI
   5 //
   6 // it is simple, returns a value of 1 or 2
   7 //
   8 #include <windows.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <math.h>
  12
  13 #include <gl\gl.h>                      // Header File For The OpenGL32 Library
  14 #include <gl\glu.h>                     // Header File For The GLu32 Library
  15 #include <gl\glaux.h>           // Header File For The Glaux Library
  16
  17 #include "globals.h"
  18 #include "bot.h"
  19 #include "gldrawlib.h"
  20 #include "fireants.h"
  21
  22 #define UP                      1
  23 #define DOWN            2
  24 #define DIRECTION(dir, val)             dir = val
  25
  26 // Our line of sight is simple, it is composed of a triangle
  27 // if the point is within that triangle, return a one
  28 // otherwise return a zero
  29
  30 //
  31 // Draw Line of Sight
  32 // where y is actually the z
  33 //
  34 void DrawLineOfSight(float x1, float y1, float x2, float y2)
  35 {
  36         float height = 0.1f;
  37
  38         glDisable(GL_LIGHTING);
  39         glDisable(GL_TEXTURE_2D);
  40
  41         glColor3f(1.0f, 1.0f, 1.0f);
  42          glBegin(GL_LINE_LOOP);
  43
  44         // Front Face
  45         glVertex3f(x1,  height,  y1);   // left bottom
  46         glVertex3f(x2,  height,  y2);   // right bottom
  47
  48         // Back Face
  49
  50
  51         glEnd();
  52
  53         glEnable(GL_LIGHTING);
  54
  55 } // end of the function
  56
  57
  58
  59 //
  60 // The algo just checks the y=mx+b of the line
  61 // and depending on the location of the vertex, etc
  62 // it is in the triangle or not
  63 // - no clipping
  64 //
  65 bool CheckSight(DriverBotPtr bot, DriverBotPtr nme)
  66 {
  67         float rad;
  68         float tmp_heading;
  69         float tmp_x2;
  70         float tmp_y2;
  71         float tmp_x3;
  72         float tmp_y3;
  73         float a1, b1, a2, b2, a3, b3, a4, b4;
  74         float m1, m2, m3;
  75         float bb1, bb2, bb3;
  76         float center_x, center_y;
  77         int direction;
  78         bool AB_vert;
  79         bool BC_vert;
  80         bool CA_vert;
  81         int inside = 0;
  82
  83         AB_vert = BC_vert = CA_vert = false;
  84
  85         // now the next point of the triangle
  86         // shift by 45 degrees
  87         tmp_heading = bot->heading + 125.0f;
  88         if (tmp_heading > 360.0f)
  89                 tmp_heading -= 360.0f;
  90
  91         rad = tmp_heading / RAD_TO_DEG;
  92
  93         tmp_x2 = LINE_OF_SIGHT * (float)cos(rad);
  94         tmp_y2 = LINE_OF_SIGHT * (float)sin(rad);
  95
  96         tmp_x2 = tmp_x2 + bot->x;
  97         tmp_y2 = (-tmp_y2) + bot->y;
  98
  99         // Now the final point
 100         tmp_heading = bot->heading + 55.0f;
 101         if (tmp_heading > 360.0f)
 102                 tmp_heading -= 360.0f;
 103
 104         rad = tmp_heading / RAD_TO_DEG;
 105
 106         tmp_x3 = LINE_OF_SIGHT * (float)cos(rad);
 107         tmp_y3 = LINE_OF_SIGHT * (float)sin(rad);
 108
 109         tmp_x3 = tmp_x3 + bot->x;
 110         tmp_y3 = (-tmp_y3) + bot->y;
 111
 112
 113         a1 = tmp_x2;
 114         b1 = tmp_y2;
 115
 116         a2 = tmp_x3;
 117         b2 = tmp_y3;
 118
 119         a3 = bot->x;
 120         b3 = bot->y;
 121
 122         a4 = nme->x;
 123         b4 = nme->y;
 124
 125
 126         // find the slope of the different lines
 127         // have to check for divide by zero also
 128         if ((a2 - a1) != 0)
 129         {
 130                 m1 = (b2 - b1) / (a2 - a1);             // a->b
 131                 bb1 = (b1)-(m1 * a1);
 132         } else if ((a2 - a1) == 0) {
 133                 AB_vert = true;
 134         } // end of the if-else
 135
 136         // y = mx + b
 137         if ((a3 - a2) != 0)
 138         {
 139                 m2 = (b3 - b2) / (a3 - a2);
 140                 bb2 = (b2)-(m2 * a2);
 141         } else if ((a3 - a2) == 0) {
 142                 BC_vert = true;
 143         } // end of if-else
 144
 145         // y = mx + b
 146         if ((a1 - a3) != 0)
 147         {
 148                 m3 = (b1 - b3) / (a1 - a3);
 149                 bb3 = (b3) - (m3 * a3);
 150         } else if ((a3 - a2) == 0) {
 151                 CA_vert = true;
 152         } // end of the if-else
 153
 154         center_x = (a1 + a2 + a3) / 3.0f;
 155         center_y = (b1 + b2 + b3) / 3.0f;
 156
 157         // a->b
 158         if (((m1 * center_x) + bb1) >= center_y)
 159                 DIRECTION(direction, UP);
 160         else
 161                 DIRECTION(direction, DOWN);
 162
 163         if (AB_vert == true) {
 164                 if ((a1 < a4) && (a1 < center_x))
 165                         inside++;
 166                 else if ((a1 > a4) && (a1 > center_x))
 167                         inside++;
 168
 169         } else {
 170                 if (direction == UP) {
 171                         if (b4 <= ((m1 * a4) + bb1))
 172                                 inside++;
 173                 } else if (direction == DOWN) {
 174                         if (b4 >= ((m1 * a4) + bb1))
 175                                 inside++;
 176                 } // end of if-else
 177
 178         } // end of the if - else
 179
 180         // b->c
 181         if (((m2 * center_x)+bb2) >= center_y)
 182                 DIRECTION(direction,UP);
 183         else
 184                 DIRECTION(direction, DOWN);
 185
 186         if (BC_vert == true) {
 187                 if (( a2 < a4) && (a2 < center_x))
 188                         inside++;
 189                 else if ((a2 > a4) && (a2 > center_x))
 190                         inside++;
 191
 192         } else {
 193                 if (direction == UP) {
 194                         if (b4 <= ((m2 * a4) + bb2))
 195                                 inside++;
 196
 197                 } else if (direction == DOWN) {
 198
 199                         if (b4 >= ((m2 * a4) + bb2))
 200                                 inside++;
 201
 202                 } // end of the if-else
 203
 204         } // end of the if-else
 205
 206         // c->a
 207         if (((m3 * center_x) + bb3) >= center_y)
 208                 DIRECTION(direction, UP);
 209         else
 210                 DIRECTION(direction, DOWN);
 211
 212         if (CA_vert == true) {
 213                 if ((a3 < a4) && (a3 < center_x))
 214                         inside++;
 215                 else if ((a3 > a4) && (a3 > center_x))
 216                         inside++;
 217         } else {
 218
 219                 if (direction == UP) {
 220                         if (b4 <= ((m3 * a4) + bb3))
 221                                 inside++;
 222
 223                 } else if (direction == DOWN) {
 224                         if (b4 >= ((m3 * a4) + bb3))
 225                                 inside++;
 226                 } // end of the if-else
 227
 228         } // end of the if-else
 229
 230 #if DRAW_LINE_SIGHT
 231         //DrawLineOfSight(bot->x, bot->y, tmp_x, tmp_y);
 232         DrawLineOfSight(tmp_x2, tmp_y2, tmp_x3, tmp_y3);
 233         DrawLineOfSight(bot->x, bot->y, tmp_x2, tmp_y2);
 234         DrawLineOfSight(bot->x, bot->y, tmp_x3, tmp_y3);
 235 #endif
 236
 237         // check if point lies inside
 238         if (inside == 3) {
 239
 240                 return true;
 241
 242         } else {
 243                 return false;
 244         } // end of if-else
 245
 246 } // end of the function