bresenhamAll & wireframe software renderer

#define IN_BOUNDS(_x,_y, _w,_h) (_x>=0 && _x<_w  &&  _y>=0 && _y<_h)
void bresenhamAll(KIT_Color* pixels,int w,int h, int x0,int y0, int x1,int y1){
  int dx=abs(x1-x0), dy=-abs(y1-y0);
  int sx,sy, psy;
  if(x0<x1){ sx=1;        } else { sx=-1;         }
  if(y0<y1){ sy=1; psy=w; } else { sy=-1; psy=-w; }
  int err=dx+dy, err2;
  int pos=x0 + y0*w;
  do {
    if(IN_BOUNDS(x0,y0, w,h)) pixels[pos].value=0xffffff00; //cyan
    if(x0==x1 && y0==y1) break;
    err2=err<<1;
    if(err2>=dy){
      if(x0==x1) break;
      err+=dy;
      x0+=sx;
      pos+=sx;
    }
    if(err2<=dx){
      if(y0==y1) break;
      err+=dx;
      y0+=sy;
      pos+=psy;
    }
  } while(1);
}
//draws wireframe triangle
int notAShader2(KIT_TTM_Canvas3D* canvas, KIT_TTM* ttms,int ttms_len, void* data){
  if(!canvas){ return 1; }  if(!ttms){ return 2; } if(!ttms_len){ return 3; }
  float v_w=canvas->v_w, v_h=canvas->v_h; int w=canvas->w, h=canvas->h;
  KIT_TTM_LockCanvas3D(canvas);
  KIT_Color* pixels=canvas->pixels; int w_half=w/2, h_half=h/2;
  for(uint32_t ttm_i=0; ttm_i<ttms_len; ++ttm_i){//for every ttm
  uint32_t objects_len=ttms[ttm_i].objects_len;
  for(uint32_t obj_i=0; obj_i<objects_len; ++obj_i){//for every object
    KIT_TTM_Object* object=&ttms[ttm_i].objects[obj_i];
      uint32_t numWorkTris=object->numWorkTris;
      if(numWorkTris==0) continue;
    KIT_TTM_Triangle* render=object->render;
      memcpy(render,object->work,sizeof(KIT_TTM_Triangle)*numWorkTris);
    for(uint32_t tri_i=0; tri_i<numWorkTris; ++tri_i){//for every triangle
      KIT_TTM_Triangle tri=render[tri_i];
      tri=KIT_TTM_ProjectTriangle(tri, w_half,h_half, v_w,v_h);
      bresenhamAll(pixels,w,h, tri.a.pos.x,tri.a.pos.y, tri.b.pos.x,tri.b.pos.y);
      bresenhamAll(pixels,w,h, tri.b.pos.x,tri.b.pos.y, tri.c.pos.x,tri.c.pos.y);
      bresenhamAll(pixels,w,h, tri.c.pos.x,tri.c.pos.y, tri.a.pos.x,tri.a.pos.y);
    }
  }}
  if(canvas->autoUnlock) KIT_TTM_UnlockCanvas3D(canvas);
  return 0;
}