add phong interpolation (lighting)

[chaz/rasterize] / vec.h

diff --git a/vec.h b/vec.h
index 614e31dfec4c0e68bdbcb5b08ae0be7399ef4ef7..48635238202c5de1a437161028112bf1085352c1 100644 (file)
--- a/vec.h
+++ b/vec.h
@@ -57,10 +57,11 @@ vec_t vec_new(scal_t x, scal_t y, scal_t z)
     return vec_new2(x, y, z, S(1.0));
 }
 
-#define VEC_ZERO    vec_new(S(0.0), S(0.0), S(0.0))
-#define VEC_ORTHO_X vec_new(S(1.0), S(0.0), S(0.0))
-#define VEC_ORTHO_Y vec_new(S(0.0), S(1.0), S(0.0))
-#define VEC_ORTHO_Z vec_new(S(0.0), S(0.0), S(1.0))
+#define VEC_ZERO      vec_new(S(0.0), S(0.0), S(0.0))
+#define VEC_ORTHO_X   vec_new(S(1.0), S(0.0), S(0.0))
+#define VEC_ORTHO_Y   vec_new(S(0.0), S(1.0), S(0.0))
+#define VEC_ORTHO_Z   vec_new(S(0.0), S(0.0), S(1.0))
+#define VEC_ZERO_FREE vec_new2(S(0.0), S(0.0), S(0.0), S(0.0))
 
 
 /*
@@ -155,6 +156,15 @@ vec_t vec_add(vec_t a, vec_t b)
     return a;
 }
 
+/*
+ * Add three vectors together.
+ */
+INLINE_MAYBE
+vec_t vec_add2(vec_t a, vec_t b, vec_t c)
+{
+    return vec_add(vec_add(a, b), c);
+}
+
 /*
  * Subtract a vector from another vector.
  */
@@ -239,5 +249,18 @@ vec_t vec_homodiv(vec_t v)
 }
 
 
+/*
+ * Interpolate smoothly between three vectors with barycentric coordinates.
+ */
+INLINE_MAYBE
+vec_t vec_interp(vec_t v1, vec_t v2, vec_t v3, scal_t b[3])
+{
+    return vec_new(v1.x * b[0] + v2.x * b[1] + v3.x * b[2],
+                   v1.y * b[0] + v2.y * b[1] + v3.y * b[2],
+                   v1.z * b[0] + v2.z * b[1] + v3.z * b[2]);
+}
+
+
+
 #endif // _VEC_H_