r_shadow.c

   1
   2 #include "quakedef.h"
   3 #include "r_shadow.h"
   4
   5 mempool_t *r_shadow_mempool;
   6
   7 int maxshadowelements;
   8 int *shadowelements;
   9 int maxtrianglefacinglight;
  10 qbyte *trianglefacinglight;
  11
  12 rtexturepool_t *r_shadow_texturepool;
  13 rtexture_t *r_shadow_attenuationtexture;
  14
  15 void r_shadow_start(void)
  16 {
  17         // allocate vertex processing arrays
  18         r_shadow_mempool = Mem_AllocPool("R_Shadow");
  19         maxshadowelements = 0;
  20         shadowelements = NULL;
  21         maxtrianglefacinglight = 0;
  22         trianglefacinglight = NULL;
  23         r_shadow_attenuationtexture = NULL;
  24         r_shadow_texturepool = NULL;
  25 }
  26
  27 void r_shadow_shutdown(void)
  28 {
  29         r_shadow_attenuationtexture = NULL;
  30         R_FreeTexturePool(&r_shadow_texturepool);
  31         maxshadowelements = 0;
  32         shadowelements = NULL;
  33         maxtrianglefacinglight = 0;
  34         trianglefacinglight = NULL;
  35         Mem_FreePool(&r_shadow_mempool);
  36 }
  37
  38 void r_shadow_newmap(void)
  39 {
  40 }
  41
  42 void R_Shadow_Init(void)
  43 {
  44         R_RegisterModule("R_Shadow", r_shadow_start, r_shadow_shutdown, r_shadow_newmap);
  45 }
  46
  47 void R_Shadow_Volume(int numverts, int numtris, float *vertex, int *elements, int *neighbors, vec3_t relativelightorigin, float lightradius, float projectdistance, int visiblevolume)
  48 {
  49         int i, *e, *n, *out, tris;
  50         float *v0, *v1, *v2, temp[3], f;
  51         if (projectdistance < 0.1)
  52         {
  53                 Con_Printf("R_Shadow_Volume: projectdistance %f\n");
  54                 return;
  55         }
  56 // terminology:
  57 //
  58 // frontface:
  59 // a triangle facing the light source
  60 //
  61 // backface:
  62 // a triangle not facing the light source
  63 //
  64 // shadow volume:
  65 // an extrusion of the backfaces, beginning at the original geometry and
  66 // ending further from the light source than the original geometry
  67 // (presumably at least as far as the light's radius, if the light has a
  68 // radius at all), capped at both front and back to avoid any problems
  69 //
  70 // description:
  71 // draws the shadow volumes of the model.
  72 // requirements:
  73 // vertex loations must already be in vertex before use.
  74 // vertex must have capacity for numverts * 2.
  75
  76         // make sure trianglefacinglight is big enough for this volume
  77         if (maxtrianglefacinglight < numtris)
  78         {
  79                 maxtrianglefacinglight = numtris;
  80                 if (trianglefacinglight)
  81                         Mem_Free(trianglefacinglight);
  82                 trianglefacinglight = Mem_Alloc(r_shadow_mempool, maxtrianglefacinglight);
  83         }
  84
  85         // make sure shadowelements is big enough for this volume
  86         if (maxshadowelements < numtris * 24)
  87         {
  88                 maxshadowelements = numtris * 24;
  89                 if (shadowelements)
  90                         Mem_Free(shadowelements);
  91                 shadowelements = Mem_Alloc(r_shadow_mempool, maxshadowelements * sizeof(int));
  92         }
  93
  94         // make projected vertices
  95         // by clever use of elements we'll construct the whole shadow from
  96         // the unprojected vertices and these projected vertices
  97         for (i = 0, v0 = vertex, v1 = vertex + numverts * 4;i < numverts;i++, v0 += 4, v1 += 4)
  98         {
  99                 VectorSubtract(v0, relativelightorigin, temp);
 100 #if 0
 101                 f = lightradius / sqrt(DotProduct(temp,temp));
 102                 if (f < 1)
 103                         f = 1;
 104                 VectorMA(relativelightorigin, f, temp, v1);
 105 #else
 106                 f = projectdistance / sqrt(DotProduct(temp,temp));
 107                 VectorMA(v0, f, temp, v1);
 108 #endif
 109         }
 110
 111         // check which triangles are facing the light
 112         for (i = 0, e = elements;i < numtris;i++, e += 3)
 113         {
 114                 // calculate triangle facing flag
 115                 v0 = vertex + e[0] * 4;
 116                 v1 = vertex + e[1] * 4;
 117                 v2 = vertex + e[2] * 4;
 118                 // we do not need to normalize the surface normal because both sides
 119                 // of the comparison use it, therefore they are both multiplied the
 120                 // same amount...  furthermore the subtract can be done on the
 121                 // vectors, saving a little bit of math in the dotproducts
 122 #if 1
 123                 // fast version
 124                 // subtracts v1 from v0 and v2, combined into a crossproduct,
 125                 // combined with a dotproduct of the light location relative to the
 126                 // first point of the triangle (any point works, since the triangle
 127                 // is obviously flat), and finally a comparison to determine if the
 128                 // light is infront of the triangle (the goal of this statement)
 129                 trianglefacinglight[i] =
 130                    (relativelightorigin[0] - v0[0]) * ((v0[1] - v1[1]) * (v2[2] - v1[2]) - (v0[2] - v1[2]) * (v2[1] - v1[1]))
 131                  + (relativelightorigin[1] - v0[1]) * ((v0[2] - v1[2]) * (v2[0] - v1[0]) - (v0[0] - v1[0]) * (v2[2] - v1[2]))
 132                  + (relativelightorigin[2] - v0[2]) * ((v0[0] - v1[0]) * (v2[1] - v1[1]) - (v0[1] - v1[1]) * (v2[0] - v1[0])) > 0;
 133 #else
 134                 // readable version
 135                 {
 136                 float dir0[3], dir1[3];
 137
 138                 // calculate two mostly perpendicular edge directions
 139                 VectorSubtract(v0, v1, dir0);
 140                 VectorSubtract(v2, v1, dir1);
 141
 142                 // we have two edge directions, we can calculate a third vector from
 143                 // them, which is the direction of the surface normal (it's magnitude
 144                 // is not 1 however)
 145                 CrossProduct(dir0, dir1, temp);
 146
 147                 // this is entirely unnecessary, but kept for clarity
 148                 //VectorNormalize(temp);
 149
 150                 // compare distance of light along normal, with distance of any point
 151                 // of the triangle along the same normal (the triangle is planar,
 152                 // I.E. flat, so all points give the same answer)
 153                 // the normal is not normalized because it is used on both sides of
 154                 // the comparison, so it's magnitude does not matter
 155                 trianglefacinglight[i] = DotProduct(relativelightorigin, temp) >= DotProduct(v0, temp);
 156 #endif
 157         }
 158
 159         // output triangle elements
 160         out = shadowelements;
 161         tris = 0;
 162
 163         // check each backface for bordering frontfaces,
 164         // and cast shadow polygons from those edges,
 165         // also create front and back caps for shadow volume
 166         for (i = 0, e = elements, n = neighbors;i < numtris;i++, e += 3, n += 3)
 167         {
 168                 if (!trianglefacinglight[i])
 169                 {
 170                         // triangle is backface and therefore casts shadow,
 171                         // output front and back caps for shadow volume
 172 #if 1
 173                         // front cap (with flipped winding order)
 174                         out[0] = e[0];
 175                         out[1] = e[2];
 176                         out[2] = e[1];
 177                         // rear cap
 178                         out[3] = e[0] + numverts;
 179                         out[4] = e[1] + numverts;
 180                         out[5] = e[2] + numverts;
 181                         out += 6;
 182                         tris += 2;
 183 #else
 184                         // rear cap
 185                         out[0] = e[0] + numverts;
 186                         out[1] = e[1] + numverts;
 187                         out[2] = e[2] + numverts;
 188                         out += 3;
 189                         tris += 1;
 190 #endif
 191                         // check the edges
 192                         if (n[0] < 0 || trianglefacinglight[n[0]])
 193                         {
 194                                 out[0] = e[0];
 195                                 out[1] = e[1];
 196                                 out[2] = e[1] + numverts;
 197                                 out[3] = e[0];
 198                                 out[4] = e[1] + numverts;
 199                                 out[5] = e[0] + numverts;
 200                                 out += 6;
 201                                 tris += 2;
 202                         }
 203                         if (n[1] < 0 || trianglefacinglight[n[1]])
 204                         {
 205                                 out[0] = e[1];
 206                                 out[1] = e[2];
 207                                 out[2] = e[2] + numverts;
 208                                 out[3] = e[1];
 209                                 out[4] = e[2] + numverts;
 210                                 out[5] = e[1] + numverts;
 211                                 out += 6;
 212                                 tris += 2;
 213                         }
 214                         if (n[2] < 0 || trianglefacinglight[n[2]])
 215                         {
 216                                 out[0] = e[2];
 217                                 out[1] = e[0];
 218                                 out[2] = e[0] + numverts;
 219                                 out[3] = e[2];
 220                                 out[4] = e[0] + numverts;
 221                                 out[5] = e[2] + numverts;
 222                                 out += 6;
 223                                 tris += 2;
 224                         }
 225                 }
 226         }
 227         R_Shadow_RenderVolume(numverts * 2, tris, shadowelements, visiblevolume);
 228 }
 229
 230 void R_Shadow_RenderVolume(int numverts, int numtris, int *elements, int visiblevolume)
 231 {
 232         // draw the volume
 233         if (visiblevolume)
 234         {
 235                 qglDisable(GL_CULL_FACE);
 236                 R_Mesh_Draw(numverts, numtris, elements);
 237                 qglEnable(GL_CULL_FACE);
 238         }
 239         else
 240         {
 241                 // increment stencil if backface is behind depthbuffer
 242                 qglCullFace(GL_BACK); // quake is backwards, this culls front faces
 243                 qglStencilOp(GL_KEEP, GL_INCR, GL_KEEP);
 244                 R_Mesh_Draw(numverts, numtris, elements);
 245                 // decrement stencil if frontface is behind depthbuffer
 246                 qglCullFace(GL_FRONT); // quake is backwards, this culls back faces
 247                 qglStencilOp(GL_KEEP, GL_DECR, GL_KEEP);
 248                 R_Mesh_Draw(numverts, numtris, elements);
 249         }
 250 }
 251
 252 static void R_Shadow_MakeTextures(void)
 253 {
 254         int x, y, z, d;
 255         float v[3];
 256         qbyte data[32][32][32][4];
 257         r_shadow_texturepool = R_AllocTexturePool();
 258         for (z = 0;z < 32;z++)
 259         {
 260                 v[2] = z - 16.0f;
 261                 for (y = 0;y < 32;y++)
 262                 {
 263                         v[1] = y - 16.0f;
 264                         for (x = 0;x < 32;x++)
 265                         {
 266                                 v[0] = x - 16.0f;
 267                                 d = (int) ((1024.0f / (DotProduct(v, v)+1)) - 8.0f);
 268                                 d = bound(0, d, 255);
 269                                 data[z][y][x][0] = data[z][y][x][1] = data[z][y][x][2] = data[z][y][x][3] = d;
 270                         }
 271                 }
 272         }
 273         r_shadow_attenuationtexture = R_LoadTexture3D(r_shadow_texturepool, "attenuation", 32, 32, 32, &data[0][0][0][0], TEXTYPE_RGBA, TEXF_PRECACHE | TEXF_ALPHA);
 274 }
 275
 276 void R_Shadow_Stage_Depth(void)
 277 {
 278         rmeshstate_t m;
 279
 280         if (!r_shadow_attenuationtexture)
 281                 R_Shadow_MakeTextures();
 282
 283         memset(&m, 0, sizeof(m));
 284         m.blendfunc1 = GL_ONE;
 285         m.blendfunc2 = GL_ZERO;
 286         R_Mesh_State(&m);
 287         GL_Color(0, 0, 0, 1);
 288 }
 289
 290 void R_Shadow_Stage_ShadowVolumes(void)
 291 {
 292         GL_Color(1, 1, 1, 1);
 293         qglColorMask(0, 0, 0, 0);
 294         qglDisable(GL_BLEND);
 295         qglDepthMask(0);
 296         qglDepthFunc(GL_LEQUAL);
 297         qglClearStencil(0);
 298         qglClear(GL_STENCIL_BUFFER_BIT);
 299         qglEnable(GL_STENCIL_TEST);
 300         qglStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 301         qglStencilFunc(GL_ALWAYS, 0, 0xFF);
 302 }
 303
 304 void R_Shadow_Stage_Light(void)
 305 {
 306         qglEnable(GL_BLEND);
 307         qglBlendFunc(GL_ONE, GL_ONE);
 308         GL_Color(1, 1, 1, 1);
 309         qglColorMask(1, 1, 1, 1);
 310         qglDepthMask(0);
 311         qglDepthFunc(GL_EQUAL);
 312         qglEnable(GL_STENCIL_TEST);
 313         qglStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 314         // only draw light where this geometry was already rendered AND the
 315         // stencil is 0 (non-zero means shadow)
 316         qglStencilFunc(GL_EQUAL, 0, 0xFF);
 317 }
 318
 319 void R_Shadow_Stage_Textures(void)
 320 {
 321         rmeshstate_t m;
 322         // attempt to restore state to what Mesh_State thinks it is
 323         qglDisable(GL_BLEND);
 324         qglBlendFunc(GL_ONE, GL_ZERO);
 325         qglDepthMask(1);
 326
 327         // now change to a more useful state
 328         memset(&m, 0, sizeof(m));
 329         m.blendfunc1 = GL_DST_COLOR;
 330         m.blendfunc2 = GL_SRC_COLOR;
 331         R_Mesh_State(&m);
 332
 333         // now hack some more
 334         GL_Color(1, 1, 1, 1);
 335         qglColorMask(1, 1, 1, 1);
 336         qglDepthFunc(GL_EQUAL);
 337         qglEnable(GL_STENCIL_TEST);
 338         qglStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 339         // only draw in lit areas
 340         qglStencilFunc(GL_EQUAL, 0, 0xFF);
 341 }
 342
 343 void R_Shadow_Stage_End(void)
 344 {
 345         rmeshstate_t m;
 346         GL_Color(1, 1, 1, 1);
 347         qglColorMask(1, 1, 1, 1);
 348         qglDepthFunc(GL_LEQUAL);
 349         qglDisable(GL_STENCIL_TEST);
 350         qglStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 351         qglStencilFunc(GL_ALWAYS, 0, 0xFF);
 352
 353         // now change to a more useful state
 354         memset(&m, 0, sizeof(m));
 355         m.blendfunc1 = GL_ONE;
 356         m.blendfunc2 = GL_ZERO;
 357         R_Mesh_State(&m);
 358 }
 359
 360 void R_Shadow_VertexLight(int numverts, float *vertex, float *normals, vec3_t relativelightorigin, float lightradius2, float lightdistbias, float lightsubtract, float *lightcolor)
 361 {
 362         int i;
 363         float *n, *v, *c, f, dist, temp[3], light[3];
 364         // calculate vertex colors
 365         VectorCopy(lightcolor, light);
 366
 367         for (i = 0, v = vertex, c = varray_color, n = normals;i < numverts;i++, v += 4, c += 4, n += 3)
 368         {
 369                 VectorSubtract(relativelightorigin, v, temp);
 370                 c[0] = 0;
 371                 c[1] = 0;
 372                 c[2] = 0;
 373                 c[3] = 1;
 374                 f = DotProduct(n, temp);
 375                 if (f > 0)
 376                 {
 377                         dist = DotProduct(temp, temp);
 378                         if (dist < lightradius2)
 379                         {
 380                                 f = ((1.0f / (dist + lightdistbias)) - lightsubtract) * (f / sqrt(dist));
 381                                 c[0] = f * light[0];
 382                                 c[1] = f * light[1];
 383                                 c[2] = f * light[2];
 384                         }
 385                 }
 386         }
 387 }