Debug drawing for simulations, to aid in visualizing abstract data such

as forces, velocities, contact points etc.

This uses a hash table to store debug elements (dots, lines, vectors at
this point). The hash table allows continuous display of elements that
are generated only in certain time steps, e.g. contact points, while
avoiding massive memory allocation. In any case, this system is really
a development feature, but very helpful in finding issues with the
internal solver data.

1 files changed, 37 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/implicit.c b/source/blender/blenkernel/intern/implicit.c
index 13403795745..d0f0bc9455a 100644
--- a/source/blender/blenkernel/intern/implicit.c
+++ b/source/blender/blenkernel/intern/implicit.c
@@ -109,6 +109,36 @@ static double itval(void)
 static float I[3][3] = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
 static float ZERO[3][3] = {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}};
 
+/* ==== hash functions for debugging ==== */
+static unsigned int hash_int_2d(unsigned int kx, unsigned int ky)
+{
+#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
+
+	unsigned int a, b, c;
+
+	a = b = c = 0xdeadbeef + (2 << 2) + 13;
+	a += kx;
+	b += ky;
+
+	c ^= b; c -= rot(b,14);
+	a ^= c; a -= rot(c,11);
+	b ^= a; b -= rot(a,25);
+	c ^= b; c -= rot(b,16);
+	a ^= c; a -= rot(c,4);
+	b ^= a; b -= rot(a,14);
+	c ^= b; c -= rot(b,24);
+
+	return c;
+
+#undef rot
+}
+
+static int hash_vertex(int type, int vertex)
+{
+	return hash_int_2d((unsigned int)type, (unsigned int)vertex);
+}
+/* ================ */
+
 /*
 #define C99
 #ifdef C99
@@ -1922,7 +1952,7 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
 	unsigned int i=0;
 	float step=0.0f, tf=clmd->sim_parms->timescale;
 	Cloth *cloth = clmd->clothObject;
-	ClothVertex *verts = cloth->verts, *cv;
+	ClothVertex *verts = cloth->verts/*, *cv*/;
 	unsigned int numverts = cloth->numverts;
 	float dt = clmd->sim_parms->timescale / clmd->sim_parms->stepsPerFrame;
 	float spf = (float)clmd->sim_parms->stepsPerFrame / clmd->sim_parms->timescale;
@@ -1943,6 +1973,12 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
 		}
 	}
 	
+	if (clmd->debug_data) {
+		for (i = 0; i < numverts; i++) {
+			BKE_sim_debug_data_add_dot(clmd->debug_data, verts[i].x, 1.0f, 0.1f, 1.0f, hash_vertex(583, i));
+		}
+	}
+	
 	while (step < tf) {
 		// damping velocity for artistic reasons
 		mul_lfvectorS(id->V, id->V, clmd->sim_parms->vel_damping, numverts);