4 mempool_t *r_shadow_mempool;
8 int maxtrianglefacinglight;
9 qbyte *trianglefacinglight;
11 void r_shadow_start(void)
13 // allocate vertex processing arrays
14 r_shadow_mempool = Mem_AllocPool("R_Shadow");
15 maxshadowelements = 0;
16 shadowelements = NULL;
17 maxtrianglefacinglight = 0;
18 trianglefacinglight = NULL;
21 void r_shadow_shutdown(void)
23 maxshadowelements = 0;
24 shadowelements = NULL;
25 maxtrianglefacinglight = 0;
26 trianglefacinglight = NULL;
27 Mem_FreePool(&r_shadow_mempool);
30 void r_shadow_newmap(void)
34 void R_Shadow_Init(void)
36 R_RegisterModule("R_Shadow", r_shadow_start, r_shadow_shutdown, r_shadow_newmap);
39 void R_Shadow_Volume(int numverts, int numtris, float *vertex, int *elements, int *neighbors, vec3_t relativelightorigin, float projectdistance, int visiblevolume)
41 int i, *e, *n, *out, tris;
42 float *v0, *v1, *v2, temp[3], f;
46 // a triangle facing the light source
49 // a triangle not facing the light source
52 // an extrusion of the backfaces, beginning at the original geometry and
53 // ending further from the light source than the original geometry
54 // (presumably at least as far as the light's radius, if the light has a
55 // radius at all), capped at both front and back to avoid any problems
58 // draws the shadow volumes of the model.
60 // vertex loations must already be in vertex before use.
61 // vertex must have capacity for numverts * 2.
63 // make sure trianglefacinglight is big enough for this volume
64 if (maxtrianglefacinglight < numtris)
66 maxtrianglefacinglight = numtris;
67 if (trianglefacinglight)
68 Mem_Free(trianglefacinglight);
69 trianglefacinglight = Mem_Alloc(r_shadow_mempool, maxtrianglefacinglight);
72 // make sure shadowelements is big enough for this volume
73 if (maxshadowelements < numtris * 24)
75 maxshadowelements = numtris * 24;
77 Mem_Free(shadowelements);
78 shadowelements = Mem_Alloc(r_shadow_mempool, maxshadowelements * sizeof(int));
81 // make projected vertices
82 // by clever use of elements we'll construct the whole shadow from
83 // the unprojected vertices and these projected vertices
84 for (i = 0, v0 = vertex, v1 = vertex + numverts * 4;i < numverts;i++, v0 += 4, v1 += 4)
86 VectorSubtract(v0, relativelightorigin, temp);
87 f = projectdistance / sqrt(DotProduct(temp,temp));
88 VectorMA(v0, f, temp, v1);
91 // check which triangles are facing the light
92 for (i = 0, e = elements;i < numtris;i++, e += 3)
94 // calculate triangle facing flag
95 v0 = vertex + e[0] * 4;
96 v1 = vertex + e[1] * 4;
97 v2 = vertex + e[2] * 4;
98 // we do not need to normalize the surface normal because both sides
99 // of the comparison use it, therefore they are both multiplied the
100 // same amount... furthermore the subtract can be done on the
101 // vectors, saving a little bit of math in the dotproducts
104 // subtracts v1 from v0 and v2, combined into a crossproduct,
105 // combined with a dotproduct of the light location relative to the
106 // first point of the triangle (any point works, since the triangle
107 // is obviously flat), and finally a comparison to determine if the
108 // light is infront of the triangle (the goal of this statement)
109 trianglefacinglight[i] =
110 (relativelightorigin[0] - v0[0]) * ((v0[1] - v1[1]) * (v2[2] - v1[2]) - (v0[2] - v1[2]) * (v2[1] - v1[1]))
111 + (relativelightorigin[1] - v0[1]) * ((v0[2] - v1[2]) * (v2[0] - v1[0]) - (v0[0] - v1[0]) * (v2[2] - v1[2]))
112 + (relativelightorigin[2] - v0[2]) * ((v0[0] - v1[0]) * (v2[1] - v1[1]) - (v0[1] - v1[1]) * (v2[0] - v1[0])) > 0;
116 float dir0[3], dir1[3],
118 // calculate two mostly perpendicular edge directions
119 VectorSubtract(v0, v1, dir0);
120 VectorSubtract(v2, v1, dir1);
122 // we have two edge directions, we can calculate a third vector from
123 // them, which is the direction of the surface normal (it's magnitude
125 CrossProduct(dir0, dir1, temp);
127 // this is entirely unnecessary, but kept for clarity
128 //VectorNormalize(temp);
130 // compare distance of light along normal, with distance of any point
131 // of the triangle along the same normal (the triangle is planar,
132 // I.E. flat, so all points give the same answer)
133 // the normal is not normalized because it is used on both sides of
134 // the comparison, so it's magnitude does not matter
135 trianglefacinglight[i] = DotProduct(relativelightorigin, temp) >= DotProduct(v0, temp);
140 // output triangle elements
141 out = shadowelements;
144 // check each backface for bordering frontfaces,
145 // and cast shadow polygons from those edges,
146 // also create front and back caps for shadow volume
147 for (i = 0, e = elements, n = neighbors;i < numtris;i++, e += 3, n += 3)
149 if (!trianglefacinglight[i])
151 // triangle is backface and therefore casts shadow,
152 // output front and back caps for shadow volume
153 // front cap (with flipped winding order)
158 out[3] = e[0] + numverts;
159 out[4] = e[1] + numverts;
160 out[5] = e[2] + numverts;
164 if (n[0] < 0 || trianglefacinglight[n[0]])
168 out[2] = e[1] + numverts;
170 out[4] = e[1] + numverts;
171 out[5] = e[0] + numverts;
175 if (n[1] < 0 || trianglefacinglight[n[1]])
179 out[2] = e[2] + numverts;
181 out[4] = e[2] + numverts;
182 out[5] = e[1] + numverts;
186 if (n[2] < 0 || trianglefacinglight[n[2]])
190 out[2] = e[0] + numverts;
192 out[4] = e[0] + numverts;
193 out[5] = e[2] + numverts;
202 qglDisable(GL_CULL_FACE);
203 R_Mesh_Draw(numverts * 2, tris, shadowelements);
204 qglEnable(GL_CULL_FACE);
208 qglColorMask(0,0,0,0);
209 qglEnable(GL_STENCIL_TEST);
210 // increment stencil if backface is behind depthbuffer
211 qglCullFace(GL_BACK); // quake is backwards, this culls front faces
212 qglStencilOp(GL_KEEP, GL_INCR, GL_KEEP);
213 R_Mesh_Draw(numverts * 2, tris, shadowelements);
214 // decrement stencil if frontface is infront of depthbuffer
215 qglCullFace(GL_FRONT); // quake is backwards, this culls back faces
216 qglStencilOp(GL_KEEP, GL_DECR, GL_KEEP);
217 R_Mesh_Draw(numverts * 2, tris, shadowelements);
218 // restore to normal quake rendering
219 qglDisable(GL_STENCIL_TEST);
220 qglStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
221 qglColorMask(1,1,1,1);
225 void R_Shadow_VertexLight(int numverts, float *vertex, float *normals, vec3_t relativelightorigin, float lightradius2, float lightdistbias, float lightsubtract, float *lightcolor)
228 float *n, *v, *c, f, dist, temp[3];
229 // calculate vertex colors
230 for (i = 0, v = vertex, c = varray_color, n = normals;i < numverts;i++, v += 4, c += 4, n += 3)
232 VectorSubtract(relativelightorigin, v, temp);
237 f = DotProduct(n, temp);
240 dist = DotProduct(temp, temp);
241 if (dist < lightradius2)
243 f = ((1.0f / (dist + lightdistbias)) - lightsubtract) * (f / sqrt(dist));
244 c[0] = f * lightcolor[0];
245 c[1] = f * lightcolor[1];
246 c[2] = f * lightcolor[2];
252 void R_Shadow_RenderLightThroughStencil(int numverts, int numtris, int *elements, vec3_t relativelightorigin, float *normals)
254 // only draw light where this geometry was already rendered AND the
255 // stencil is 0 (non-zero means shadow)
256 qglDepthFunc(GL_EQUAL);
257 qglEnable(GL_STENCIL_TEST);
258 qglStencilFunc(GL_EQUAL, 0, 0xFF);
259 R_Mesh_Draw(numverts, numtris, elements);
260 qglDisable(GL_STENCIL_TEST);
261 qglDepthFunc(GL_LEQUAL);
264 void R_Shadow_ClearStencil(void)
267 qglClear(GL_STENCIL_BUFFER_BIT);