Split interp_weights_face_v3 into specific functions for tris and quads

This splits `interp_weights_face_v3` into `interp_weights_tri_v3` and
`interp_weights_quad_v3`, in order to properly handle three sided polygons
without needing a useless extra index in your weight array. This also
improves clarity and consistency with other math_geom functions, thus
reducing potential future errors.

Reviewed By: mont29

Differential Revision: https://developer.blender.org/D2461

7 files changed, 52 insertions, 48 deletions

diff --git a/source/blender/blenkernel/intern/collision.c b/source/blender/blenkernel/intern/collision.c
index 18ca1407ba0..ee25be36855 100644
--- a/source/blender/blenkernel/intern/collision.c
+++ b/source/blender/blenkernel/intern/collision.c
@@ -1014,7 +1014,7 @@ static bool cloth_points_collision_response_static(ClothModifierData *clmd, Coll
 }
 
 BLI_INLINE bool cloth_point_face_collision_params(const float p1[3], const float p2[3], const float v0[3], const float v1[3], const float v2[3],
-                                                  float r_nor[3], float *r_lambda, float r_w[4])
+                                                  float r_nor[3], float *r_lambda, float r_w[3])
 {
 	float edge1[3], edge2[3], p2face[3], p1p2[3], v0p2[3];
 	float nor_v0p2, nor_p1p2;
@@ -1026,7 +1026,7 @@ BLI_INLINE bool cloth_point_face_collision_params(const float p1[3], const float
 	
 	nor_v0p2 = dot_v3v3(v0p2, r_nor);
 	madd_v3_v3v3fl(p2face, p2, r_nor, -nor_v0p2);
-	interp_weights_face_v3(r_w, v0, v1, v2, NULL, p2face);
+	interp_weights_tri_v3(r_w, v0, v1, v2, p2face);
 	
 	sub_v3_v3v3(p1p2, p2, p1);
 	sub_v3_v3v3(v0p2, p2, v0);
@@ -1085,7 +1085,7 @@ static CollPair *cloth_point_collpair(
 	const float *co1 = mverts[bp1].co, *co2 = mverts[bp2].co, *co3 = mverts[bp3].co;
 	float lambda /*, distance1 */, distance2;
 	float facenor[3], v1p1[3], v1p2[3];
-	float w[4];
+	float w[3];
 
 	if (!cloth_point_face_collision_params(p1, p2, co1, co2, co3, facenor, &lambda, w))
 		return collpair;
diff --git a/source/blender/blenkernel/intern/dynamicpaint.c b/source/blender/blenkernel/intern/dynamicpaint.c
index 4d9e314afc4..1d198e36e05 100644
--- a/source/blender/blenkernel/intern/dynamicpaint.c
+++ b/source/blender/blenkernel/intern/dynamicpaint.c
@@ -3739,7 +3739,7 @@ static void dynamic_paint_paint_mesh_cell_point_cb_ex(
 
 		/* velocity brush, only do on main sample */
 		if (brush->flags & MOD_DPAINT_USES_VELOCITY && ss == 0 && brushVelocity) {
-			float weights[4];
+			float weights[3];
 			float brushPointVelocity[3];
 			float velocity[3];
 
@@ -3748,7 +3748,7 @@ static void dynamic_paint_paint_mesh_cell_point_cb_ex(
 			const int v3 = mloop[mlooptri[hitTri].tri[2]].v;
 
 			/* calculate barycentric weights for hit point */
-			interp_weights_face_v3(weights, mvert[v1].co, mvert[v2].co, mvert[v3].co, NULL, hitCoord);
+			interp_weights_tri_v3(weights, mvert[v1].co, mvert[v2].co, mvert[v3].co, hitCoord);
 
 			/* simple check based on brush surface velocity,
 			 *  todo: perhaps implement something that handles volume movement as well */
diff --git a/source/blender/blenkernel/intern/smoke.c b/source/blender/blenkernel/intern/smoke.c
index e8970d416e9..d0ef5cfc092 100644
--- a/source/blender/blenkernel/intern/smoke.c
+++ b/source/blender/blenkernel/intern/smoke.c
@@ -758,15 +758,14 @@ static void obstacles_from_derivedmesh_task_cb(void *userdata, const int z)
 			/* find the nearest point on the mesh */
 			if (BLI_bvhtree_find_nearest(data->tree->tree, ray_start, &nearest, data->tree->nearest_callback, data->tree) != -1) {
 				const MLoopTri *lt = &data->looptri[nearest.index];
-				float weights[4];
+				float weights[3];
 				int v1, v2, v3;
 
 				/* calculate barycentric weights for nearest point */
 				v1 = data->mloop[lt->tri[0]].v;
 				v2 = data->mloop[lt->tri[1]].v;
 				v3 = data->mloop[lt->tri[2]].v;
-				interp_weights_face_v3(
-				            weights, data->mvert[v1].co, data->mvert[v2].co, data->mvert[v3].co, NULL, nearest.co);
+				interp_weights_tri_v3(weights, data->mvert[v1].co, data->mvert[v2].co, data->mvert[v3].co, nearest.co);
 
 				// DG TODO
 				if (data->has_velocity)
@@ -1454,7 +1453,7 @@ static void sample_derivedmesh(
 
 	/* find the nearest point on the mesh */
 	if (BLI_bvhtree_find_nearest(treeData->tree, ray_start, &nearest, treeData->nearest_callback, treeData) != -1) {
-		float weights[4];
+		float weights[3];
 		int v1, v2, v3, f_index = nearest.index;
 		float n1[3], n2[3], n3[3], hit_normal[3];
 
@@ -1471,7 +1470,7 @@ static void sample_derivedmesh(
 		v1 = mloop[mlooptri[f_index].tri[0]].v;
 		v2 = mloop[mlooptri[f_index].tri[1]].v;
 		v3 = mloop[mlooptri[f_index].tri[2]].v;
-		interp_weights_face_v3(weights, mvert[v1].co, mvert[v2].co, mvert[v3].co, NULL, nearest.co);
+		interp_weights_tri_v3(weights, mvert[v1].co, mvert[v2].co, mvert[v3].co, nearest.co);
 
 		if (sfs->flags & MOD_SMOKE_FLOW_INITVELOCITY && velocity_map) {
 			/* apply normal directional velocity */
diff --git a/source/blender/blenlib/BLI_math_geom.h b/source/blender/blenlib/BLI_math_geom.h
index b5007b29f4c..d33c2cb3279 100644
--- a/source/blender/blenlib/BLI_math_geom.h
+++ b/source/blender/blenlib/BLI_math_geom.h
@@ -323,10 +323,8 @@ bool clip_segment_v3_plane_n(
         float r_p1[3], float r_p2[3]);
 
 /****************************** Interpolation ********************************/
-
-/* tri or quad, d can be NULL */
-void interp_weights_face_v3(float w[4],
-                            const float a[3], const float b[3], const float c[3], const float d[3], const float p[3]);
+void interp_weights_tri_v3(float w[3], const float a[3], const float b[3], const float c[3], const float p[3]);
+void interp_weights_quad_v3(float w[4], const float a[3], const float b[3], const float c[3], const float d[3], const float p[3]);
 void interp_weights_poly_v3(float w[], float v[][3], const int n, const float co[3]);
 void interp_weights_poly_v2(float w[], float v[][2], const int n, const float co[2]);
 
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index 76dac5487f2..74ede1e7559 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -2950,7 +2950,15 @@ static bool barycentric_weights(const float v1[3], const float v2[3], const floa
 	}
 }
 
-void interp_weights_face_v3(float w[4], const float v1[3], const float v2[3], const float v3[3], const float v4[3], const float co[3])
+void interp_weights_tri_v3(float w[3], const float v1[3], const float v2[3], const float v3[3], const float co[3])
+{
+	float n[3];
+
+	normal_tri_v3(n, v1, v2, v3);
+	barycentric_weights(v1, v2, v3, co, n, w);
+}
+
+void interp_weights_quad_v3(float w[4], const float v1[3], const float v2[3], const float v3[3], const float v4[3], const float co[3])
 {
 	float w2[3];
 
@@ -2963,7 +2971,7 @@ void interp_weights_face_v3(float w[4], const float v1[3], const float v2[3], co
 		w[1] = 1.0f;
 	else if (equals_v3v3(co, v3))
 		w[2] = 1.0f;
-	else if (v4 && equals_v3v3(co, v4))
+	else if (equals_v3v3(co, v4))
 		w[3] = 1.0f;
 	else {
 		/* otherwise compute barycentric interpolation weights */
@@ -2971,35 +2979,24 @@ void interp_weights_face_v3(float w[4], const float v1[3], const float v2[3], co
 		bool degenerate;
 
 		sub_v3_v3v3(n1, v1, v3);
-		if (v4) {
-			sub_v3_v3v3(n2, v2, v4);
-		}
-		else {
-			sub_v3_v3v3(n2, v2, v3);
-		}
+		sub_v3_v3v3(n2, v2, v4);
 		cross_v3_v3v3(n, n1, n2);
 
-		/* OpenGL seems to split this way, so we do too */
-		if (v4) {
-			degenerate = barycentric_weights(v1, v2, v4, co, n, w);
-			SWAP(float, w[2], w[3]);
-
-			if (degenerate || (w[0] < 0.0f)) {
-				/* if w[1] is negative, co is on the other side of the v1-v3 edge,
-				 * so we interpolate using the other triangle */
-				degenerate = barycentric_weights(v2, v3, v4, co, n, w2);
-
-				if (!degenerate) {
-					w[0] = 0.0f;
-					w[1] = w2[0];
-					w[2] = w2[1];
-					w[3] = w2[2];
-				}
+		degenerate = barycentric_weights(v1, v2, v4, co, n, w);
+		SWAP(float, w[2], w[3]);
+
+		if (degenerate || (w[0] < 0.0f)) {
+			/* if w[1] is negative, co is on the other side of the v1-v3 edge,
+			 * so we interpolate using the other triangle */
+			degenerate = barycentric_weights(v2, v3, v4, co, n, w2);
+
+			if (!degenerate) {
+				w[0] = 0.0f;
+				w[1] = w2[0];
+				w[2] = w2[1];
+				w[3] = w2[2];
 			}
 		}
-		else {
-			barycentric_weights(v1, v2, v3, co, n, w);
-		}
 	}
 }
 
diff --git a/source/blender/render/intern/source/convertblender.c b/source/blender/render/intern/source/convertblender.c
index 86961cdd169..263ea3d4ef2 100644
--- a/source/blender/render/intern/source/convertblender.c
+++ b/source/blender/render/intern/source/convertblender.c
@@ -5569,12 +5569,17 @@ static void calculate_speedvectors(Render *re, ObjectInstanceRen *obi, float *ve
 					/* interpolate speed vectors from strand surface */
 					face= mesh->face[*index];
 
-					co1= mesh->co[face[0]];
-					co2= mesh->co[face[1]];
-					co3= mesh->co[face[2]];
-					co4= (face[3])? mesh->co[face[3]]: NULL;
+					co1 = mesh->co[face[0]];
+					co2 = mesh->co[face[1]];
+					co3 = mesh->co[face[2]];
 
-					interp_weights_face_v3(w, co1, co2, co3, co4, strand->vert->co);
+					if (face[3]) {
+						co4 = mesh->co[face[3]];
+						interp_weights_quad_v3(w, co1, co2, co3, co4, strand->vert->co);
+					}
+					else {
+						interp_weights_tri_v3(w, co1, co2, co3, strand->vert->co);
+					}
 
 					zero_v4(speed);
 					madd_v4_v4fl(speed, winspeed[face[0]], w[0]);
diff --git a/source/blender/render/intern/source/occlusion.c b/source/blender/render/intern/source/occlusion.c
index ddcd2e84520..cd93898d846 100644
--- a/source/blender/render/intern/source/occlusion.c
+++ b/source/blender/render/intern/source/occlusion.c
@@ -1190,9 +1190,14 @@ static void sample_occ_surface(ShadeInput *shi)
 		co1 = mesh->co[face[0]];
 		co2 = mesh->co[face[1]];
 		co3 = mesh->co[face[2]];
-		co4 = (face[3]) ? mesh->co[face[3]] : NULL;
 
-		interp_weights_face_v3(w, co1, co2, co3, co4, strand->vert->co);
+		if (face[3]) {
+			co4 = mesh->co[face[3]];
+			interp_weights_quad_v3(w, co1, co2, co3, co4, strand->vert->co);
+		}
+		else {
+			interp_weights_tri_v3(w, co1, co2, co3, strand->vert->co);
+		}
 
 		zero_v3(shi->ao);
 		zero_v3(shi->env);