Function collide

source/src/physics.cpp:213–351

// drop & rise are supplied by the physics below to indicate gravity/push for current mini-timestep

bool collide(physent *d, bool spawn, float drop, float rise)
{
    cornersurface = 0;
    const float fx1 = d->o.x-d->radius;     // figure out integer cube rectangle this entity covers in map
    const float fy1 = d->o.y-d->radius;
    const float fx2 = d->o.x+d->radius;
    const float fy2 = d->o.y+d->radius;
    const int x1 = int(fx1);
    const int y1 = int(fy1);
    const int x2 = int(fx2);
    const int y2 = int(fy2);
    float hi = 127, lo = -128;
    const float eyeheight = d->eyeheight;
    const float playerheight = eyeheight + d->aboveeye;
    float z1 = d->o.z-eyeheight, z2 = z1 + playerheight;
    if(d->type != ENT_BOUNCE) z1 += 1.26;
    const int applyclip = d->type == ENT_BOT || d->type == ENT_PLAYER || (d->type == ENT_BOUNCE && ((bounceent *)d)->plclipped) ? TAGANYCLIP : TAGCLIP;

    for(int y = y1; y<=y2; y++) for(int x = x1; x<=x2; x++)     // collide with map
    {
        if(OUTBORD(x,y)) return true;
        sqr *s = S(x,y);
        bool tagclipped = (s->tag & applyclip) != 0;
        float ceil = s->ceil;
        float floor = s->floor;
        switch(s->type)
        {
            case SOLID:
                return true;

            case CORNER:
            {
                sqr *ns, *h = NULL;
                int bx, by, bs;
                int q = cornertest(x, y, bx, by, bs, ns, h);
                bool matter = false, match = false;
                switch(q)                          //  0XX3
                {                                  //  XXXX
                    case 0:                        //  1XX2
                        match = x==x2 && y==y2;
                        matter = fx2-bx+fy2-by>=bs;
                        break;
                    case 1:
                        match = x==x2 && y==y1;
                        matter = fx2-bx>=fy1-by;
                        break;
                    case 2:
                        match = x==x1 && y==y1;
                        matter = fx1-bx+fy1-by<=bs;
                        break;
                    case 3:
                        match = x==x1 && y==y2;
                        matter = fx1-bx<=fy2-by;
                        break;
                    default:
                        return true; // mapper's fault: corner with unsufficient solids: renderer can't handle those anyway: treat as solid
                }
                cornersurface = (q & 1) ? 5 : 6;