src/engine/lightning.h

   1 #define MAXLIGHTNINGSTEPS 64
   2 #define LIGHTNINGSTEP 8
   3 int lnjitterx[MAXLIGHTNINGSTEPS], lnjittery[MAXLIGHTNINGSTEPS];
   4 int lastlnjitter = 0;
   5
   6 VAR(lnjittermillis, 0, 100, 1000);
   7 VAR(lnjitterradius, 0, 2, 100);
   8
   9 static void setuplightning()
  10 {
  11     if(lastmillis-lastlnjitter > lnjittermillis)
  12     {
  13         lastlnjitter = lastmillis - (lastmillis%lnjittermillis);
  14         loopi(MAXLIGHTNINGSTEPS)
  15         {
  16             lnjitterx[i] = -lnjitterradius + rnd(2*lnjitterradius + 1);
  17             lnjittery[i] = -lnjitterradius + rnd(2*lnjitterradius + 1);
  18         }
  19     }
  20 }
  21
  22 static void renderlightning(const vec &o, const vec &d, float sz, float tx, float ty, float tsz)
  23 {
  24     vec step(d);
  25     step.sub(o);
  26     float len = step.magnitude();
  27     int numsteps = clamp(int(ceil(len/LIGHTNINGSTEP)), 2, MAXLIGHTNINGSTEPS);
  28     step.div(numsteps+1);
  29     int jitteroffset = detrnd(int(o.x+o.y+o.z), MAXLIGHTNINGSTEPS);
  30     vec cur(o), up, right;
  31     up.orthogonal(step);
  32     up.normalize();
  33     right.cross(up, step);
  34     right.normalize();
  35     glBegin(GL_QUAD_STRIP);
  36     loopj(numsteps)
  37     {
  38         vec next(cur);
  39         next.add(step);
  40         if(j+1==numsteps) next = d;
  41         else
  42         {
  43             next.add(vec(right).mul(sz*lnjitterx[(j+jitteroffset)%MAXLIGHTNINGSTEPS]));
  44             next.add(vec(up).mul(sz*lnjittery[(j+jitteroffset)%MAXLIGHTNINGSTEPS]));
  45         }
  46         vec dir1 = next, dir2 = next, across;
  47         dir1.sub(cur);
  48         dir2.sub(camera1->o);
  49         across.cross(dir2, dir1).normalize().mul(sz);
  50         float tx1 = j&1 ? tx : tx+tsz, tx2 = j&1 ? tx+tsz : tx;
  51         glTexCoord2f(tx2, ty+tsz); glVertex3f(cur.x-across.x, cur.y-across.y, cur.z-across.z);
  52         glTexCoord2f(tx2, ty);     glVertex3f(cur.x+across.x, cur.y+across.y, cur.z+across.z);
  53         if(j+1==numsteps)
  54         {
  55             glTexCoord2f(tx1, ty+tsz); glVertex3f(next.x-across.x, next.y-across.y, next.z-across.z);
  56             glTexCoord2f(tx1, ty);     glVertex3f(next.x+across.x, next.y+across.y, next.z+across.z);
  57         }
  58         cur = next;
  59     }
  60     glEnd();
  61 }
  62
  63 struct lightningrenderer : listrenderer
  64 {
  65     lightningrenderer()
  66         : listrenderer("packages/particles/lightning.jpg", PT_LIGHTNING|PT_TRACK|PT_GLARE, 0, 0)
  67     {}
  68
  69     void startrender()
  70     {
  71         glDisable(GL_CULL_FACE);
  72     }
  73
  74     void endrender()
  75     {
  76         glEnable(GL_CULL_FACE);
  77     }
  78
  79     void update()
  80     {
  81         setuplightning();
  82     }
  83
  84     void renderpart(listparticle *p, const vec &o, const vec &d, int blend, int ts, uchar *color)
  85     {
  86         blend = min(blend<<2, 255);
  87         if(type&PT_MOD) //multiply alpha into color
  88             glColor3ub((color[0]*blend)>>8, (color[1]*blend)>>8, (color[2]*blend)>>8);
  89         else
  90             glColor4ub(color[0], color[1], color[2], blend);
  91         float tx = 0, ty = 0, tsz = 1;
  92         if(type&PT_RND4)
  93         {
  94             int i = detrnd((size_t)p, 4);
  95             tx = 0.5f*(i&1);
  96             ty = 0.5f*((i>>1)&1);
  97             tsz = 0.5f;
  98         }
  99         renderlightning(o, d, p->size, tx, ty, tsz);
 100     }
 101 };
 102 static lightningrenderer lightnings;
 103