Dogcows Code - chaz/rasterize/blob - triangle.hh

   1
   2 /*
   3  * CS5600 University of Utah
   4  * Charles McGarvey
   5  * mcgarvey@eng.utah.edu
   6  */
   7
   8 #ifndef _TRIANGLE_HH_
   9 #define _TRIANGLE_HH_
  10
  11 #include "element.hh"
  12
  13
  14 namespace rt {
  15
  16
  17 /*
  18  * A class for a triangle object.
  19  */
  20 class triangle : public element
  21 {
  22     vec_t   a;
  23     vec_t   b;
  24     vec_t   c;
  25
  26 public:
  27
  28     triangle(vec_t a, vec_t b, vec_t c) :
  29         a(a), b(b), c(c)
  30     {}
  31
  32     virtual ~triangle()
  33     {}
  34
  35     virtual bool intersect(ray_t ray, contact_t& hit) const
  36     {
  37         plane p = plane(a, b, c);
  38         if (!p.intersect(ray, hit)) {
  39             return false;
  40         }
  41
  42         scal_t bc[3];
  43         if (!barycentric(bc, hit.p)) {
  44             return false;
  45         }
  46
  47 #if QUIRKS
  48         if (vec_dot(p.normal(), hit.n) < S(0.0)) {
  49             hit.n = vec_neg(hit.n);
  50         }
  51 #endif
  52
  53         return true;
  54     }
  55
  56     /*
  57      * Calculate barycentric coordinates for the triangle.
  58      */
  59     bool barycentric(scal_t* bc, vec_t v) const
  60     {
  61         scal_t denom = (b.y - c.y) * (a.x - c.x) + (c.x - b.x) * (a.y - c.y);
  62         bc[0] = ((b.y - c.y) * (v.x - c.x) + (c.x - b.x) * (v.y - c.y)) / denom;
  63         bc[1] = ((c.y - a.y) * (v.x - c.x) + (a.x - c.x) * (v.y - c.y)) / denom;
  64         bc[2] = S(1.0) - bc[0] - bc[1];
  65         if (S(0.0) <= bc[0] && bc[0] <= S(1.0) &&
  66             S(0.0) <= bc[1] && bc[1] <= S(1.0) &&
  67             S(0.0) <= bc[2] && bc[2] <= S(1.0)) {
  68             return true;
  69         }
  70         return false;
  71     }
  72
  73     virtual vec_t txcoord(vec_t point) const
  74     {
  75         vec_t t1 = vec_new(S(0.0), S(0.0), S(0.0));
  76         vec_t t2 = vec_new(S(1.0), S(0.0), S(0.0));
  77         vec_t t3 = vec_new(S(1.0), S(1.0), S(0.0));
  78         scal_t bc[3];
  79         barycentric(bc, point);
  80         return vec_interp(t1, t2, t3, bc);
  81     }
  82 };
  83
  84
  85 /*
  86  * Destroy a new'd triangle, releasing its memory.
  87  */
  88 INLINE_MAYBE
  89 void triangle_destroy(plane* t)
  90 {
  91     delete t;
  92 }
  93
  94
  95 } // namespace rt
  96
  97 #endif // _PLANE_HH_
  98
  99