Function lightray

source/src/worldlight.cpp:7–116

VAR(lightscale,1,4,100);

void lightray(float bx, float by, const persistent_entity &light, float fade = 1, bool flicker = false)     // done in realtime, needs to be fast
{
    float lx = light.x+(flicker ? (rnd(21)-10)*0.1f : 0);
    float ly = light.y+(flicker ? (rnd(21)-10)*0.1f : 0);
    float dx = bx-lx;
    float dy = by-ly;
    float dist = sqrtf(dx*dx+dy*dy);
    if(dist<1.0f) return;
    int reach = light.attr1;
    int steps = (int)(reach*reach*1.6f/dist); // can change this for speedup/quality?
    const int PRECBITS = 12;
    const float PRECF = 4096.0f;
    int x = (int)(lx*PRECF);
    int y = (int)(ly*PRECF);
    int fadescale = (int)(fade*PRECF);
    int l = light.attr2*fadescale;
    int stepx = (int)(dx/(float)steps*PRECF);
    int stepy = (int)(dy/(float)steps*PRECF);
    int stepl = (int)(l/(float)steps); // incorrect: light will fade quicker if near edge of the world

    if(maxtmus)
    {
        l /= lightscale;
        stepl /= lightscale;

        if(light.attr3 || light.attr4)      // coloured light version, special case because most lights are white
        {
            if(flicker)
            {
                int dimness = rnd((((255<<PRECBITS)-(int(light.attr2)+int(light.attr3)+int(light.attr4))*fadescale/3)>>(PRECBITS+4))+1);
                x += stepx*dimness;
                y += stepy*dimness;
            }

            if(OUTBORD(x>>PRECBITS, y>>PRECBITS)) return;

            int g = light.attr3*fadescale;
            int stepg = (int)(g/(float)steps);
            int b = light.attr4*fadescale;
            int stepb = (int)(b/(float)steps);
            g /= lightscale;
            stepg /= lightscale;
            b /= lightscale;
            stepb /= lightscale;
            loopi(steps)
            {
                sqr *s = S(x>>PRECBITS, y>>PRECBITS);
                s->r = min((l>>PRECBITS)+s->r, 255);
                s->g = min((g>>PRECBITS)+s->g, 255);
                s->b = min((b>>PRECBITS)+s->b, 255);
                if(SOLID(s)) return;
                x += stepx;
                y += stepy;
                l -= stepl;
                g -= stepg;
                b -= stepb;
                stepl -= 25;
                stepg -= 25;