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 "color.hh"
  12 #include "element.hh"
  13
  14
  15 namespace rt {
  16
  17
  18 /*
  19  * A class for a triangle object.
  20  */
  21 class triangle : public element
  22 {
  23 public:
  24
  25     color_t material;
  26     vec_t   a;
  27     vec_t   b;
  28     vec_t   c;
  29
  30     triangle(vec_t a, vec_t b, vec_t c, color_t color = COLOR_WHITE) :
  31         a(a), b(b), c(c), material(color)
  32     {}
  33
  34     virtual ~triangle()
  35     {}
  36
  37     virtual bool intersect(ray_t ray, contact_t& hit) const
  38     {
  39         plane p = plane(a, b, c);
  40         if (!p.intersect(ray, hit)) {
  41             return false;
  42         }
  43
  44         scal_t bc[3];
  45         if (barycentric(bc, hit.p)) {
  46             return true;
  47         }
  48
  49         return false;
  50     }
  51
  52     virtual color_t color(vec_t point) const
  53     {
  54         return material;
  55     }
  56
  57     /*
  58      * Calculate barycentric coordinates for the triangle.
  59      */
  60     bool barycentric(scal_t* bc, vec_t v) const
  61     {
  62         scal_t denom = (b.y - c.y) * (a.x - c.x) + (c.x - b.x) * (a.y - c.y);
  63         bc[0] = ((b.y - c.y) * (v.x - c.x) + (c.x - b.x) * (v.y - c.y)) / denom;
  64         bc[1] = ((c.y - a.y) * (v.x - c.x) + (a.x - c.x) * (v.y - c.y)) / denom;
  65         bc[2] = S(1.0) - bc[0] - bc[1];
  66         if (S(0.0) <= bc[0] && bc[0] <= S(1.0) &&
  67             S(0.0) <= bc[1] && bc[1] <= S(1.0) &&
  68             S(0.0) <= bc[2] && bc[2] <= S(1.0)) {
  69             return true;
  70         }
  71         return false;
  72     }
  73 };
  74
  75
  76 /*
  77  * Destroy a new'd triangle, releasing its memory.
  78  */
  79 INLINE_MAYBE
  80 void triangle_destroy(plane* t)
  81 {
  82     delete t;
  83 }
  84
  85
  86 } // namespace rt
  87
  88 #endif // _PLANE_HH_
  89
  90