Dogcows Code - chaz/rasterize/blob - tri.h

   1
   2 /*
   3  * CS5600 University of Utah
   4  * Charles McGarvey
   5  * mcgarvey@eng.utah.edu
   6  */
   7
   8 #ifndef __TRI_H__
   9 #define __TRI_H__
  10
  11 #include "mat.h"
  12 #include "vert.h"
  13
  14
  15 /*
  16  * A triangle is a polygon of three vertices.
  17  */
  18 struct tri
  19 {
  20     vert_t a;
  21     vert_t b;
  22     vert_t c;
  23 };
  24 typedef struct tri tri_t;
  25
  26 /*
  27  * Initialize a triangle.
  28  */
  29 __fast__
  30 void tri_init(tri_t* t, vert_t a, vert_t b, vert_t c)
  31 {
  32     t->a = a;
  33     t->b = b;
  34     t->c = c;
  35 }
  36
  37
  38 /*
  39  * Create a new triangle.
  40  */
  41 __fast__
  42 tri_t tri_new(vert_t a, vert_t b, vert_t c)
  43 {
  44     tri_t t;
  45     tri_init(&t, a, b, c);
  46     return t;
  47 }
  48
  49 #define TRI_ZERO tri_new(VERT_ZERO, VERT_ZERO, VERT_ZERO)
  50
  51
  52 /*
  53  * Create a new triangle on the heap.
  54  */
  55 __fast__
  56 tri_t* tri_alloc(vert_t a, vert_t b, vert_t c)
  57 {
  58     tri_t* t = (tri_t*)mem_alloc(sizeof(tri_t));
  59     tri_init(t, a, b, c);
  60     return t;
  61 }
  62
  63
  64 /*
  65  * Apply a transformation matrix to alter the triangle geometry.
  66  */
  67 __fast__
  68 tri_t tri_transform(tri_t t, mat_t m)
  69 {
  70     t.a.v = mat_apply(m, t.a.v);
  71     t.b.v = mat_apply(m, t.b.v);
  72     t.c.v = mat_apply(m, t.c.v);
  73     return t;
  74 }
  75
  76
  77 /*
  78  * Get the barycentric coordinates of a vector against a triangle.  The
  79  * returned coordinates will be a linear combination, but they may not
  80  * actually be barycentric coordinates.  Use the function vec_is_barycentric
  81  * to check if they really are barycentric coordinates, meaning the point
  82  * vector v is inside the triangle, ignoring the Z components.
  83  */
  84 vec_t tri_barycentric(const tri_t* t, vec_t v);
  85
  86
  87 #endif // __TRI_H__
  88