diff options
Diffstat (limited to 'source/blender/blenlib/intern/math_geom.c')
| -rw-r--r-- | source/blender/blenlib/intern/math_geom.c | 42 |
1 files changed, 24 insertions, 18 deletions
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c index 01dbe01d152..45e8c425f64 100644 --- a/source/blender/blenlib/intern/math_geom.c +++ b/source/blender/blenlib/intern/math_geom.c @@ -88,6 +88,27 @@ float normal_quad_v3(float n[3], const float v1[3], const float v2[3], const flo return normalize_v3(n); } +/** + * Computes the normal of a planar + * polygon See Graphics Gems for + * computing newell normal. + */ +float normal_poly_v3(float n[3], const float verts[][3], unsigned int nr) +{ + float const *v_prev = verts[nr - 1]; + float const *v_curr = verts[0]; + unsigned int i; + + zero_v3(n); + + /* Newell's Method */ + for (i = 0; i < nr; v_prev = v_curr, v_curr = verts[++i]) { + add_newell_cross_v3_v3v3(n, v_prev, v_curr); + } + + return normalize_v3(n); +} + /* only convex Quadrilaterals */ float area_quad_v3(const float v1[3], const float v2[3], const float v3[3], const float v4[3]) { @@ -134,25 +155,10 @@ float area_tri_signed_v3(const float v1[3], const float v2[3], const float v3[3] return area; } -float area_poly_v3(const float verts[][3], unsigned int nr, const float normal[3]) +float area_poly_v3(const float verts[][3], unsigned int nr) { - unsigned int a; - int px, py; - const float max = axis_dominant_v3_max(&px, &py, normal); - float area; - const float *co_curr, *co_prev; - - /* The Trapezium Area Rule */ - co_prev = verts[nr - 1]; - co_curr = verts[0]; - area = 0.0f; - for (a = 0; a < nr; a++) { - area += (co_curr[px] - co_prev[px]) * (co_curr[py] + co_prev[py]); - co_prev = co_curr; - co_curr += 3; - } - - return fabsf(0.5f * area / max); + float n[3]; + return normal_poly_v3(n, verts, nr) * 0.5f; } float cross_poly_v2(const float verts[][2], unsigned int nr) |