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.

3 files changed, 168 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_effect.h b/source/blender/blenkernel/BKE_effect.h
index d5e54d849cd..d6991a473b0 100644
--- a/source/blender/blenkernel/BKE_effect.h
+++ b/source/blender/blenkernel/BKE_effect.h
@@ -136,6 +136,32 @@ int get_effector_data(struct EffectorCache *eff, struct EffectorData *efd, struc
 /* EffectorData->flag */
 #define PE_VELOCITY_TO_IMPULSE  1
 
+/* ======== Simulation Debugging ======== */
+
+typedef struct SimDebugElement {
+	int type;
+	int hash;
+	float color[3];
+	
+	float v1[3], v2[3];
+} SimDebugElement;
+
+typedef enum eSimDebugElement_Type {
+	SIM_DEBUG_ELEM_DOT,
+	SIM_DEBUG_ELEM_LINE,
+	SIM_DEBUG_ELEM_VECTOR,
+} eSimDebugElement_Type;
+
+typedef struct SimDebugData {
+	struct GHash *gh;
+} SimDebugData;
+
+struct SimDebugData *BKE_sim_debug_data_new(void);
+void BKE_sim_debug_data_add_dot(struct SimDebugData *debug_data, const float p[3], float r, float g, float b, int hash);
+void BKE_sim_debug_data_add_line(struct SimDebugData *debug_data, const float p1[3], const float p2[3], float r, float g, float b, int hash);
+void BKE_sim_debug_data_add_vector(struct SimDebugData *debug_data, const float p[3], const float d[3], float r, float g, float b, int hash);
+void BKE_sim_debug_data_clear(struct SimDebugData *debug_data);
+void BKE_sim_debug_data_free(struct SimDebugData *debug_data);
 
 #endif
 
diff --git a/source/blender/blenkernel/intern/effect.c b/source/blender/blenkernel/intern/effect.c
index ced9da8d0b1..94b4af10201 100644
--- a/source/blender/blenkernel/intern/effect.c
+++ b/source/blender/blenkernel/intern/effect.c
@@ -51,6 +51,7 @@
 #include "BLI_noise.h"
 #include "BLI_rand.h"
 #include "BLI_utildefines.h"
+#include "BLI_ghash.h"
 
 #include "PIL_time.h"
 
@@ -1024,3 +1025,107 @@ void pdDoEffectors(ListBase *effectors, ListBase *colliders, EffectorWeights *we
 		}
 	}
 }
+
+/* ======== Simulation Debugging ======== */
+
+static unsigned int debug_element_hash(const void *key)
+{
+	const SimDebugElement *elem = key;
+	return elem->hash;
+}
+
+static int debug_element_compare(const void *a, const void *b)
+{
+	const SimDebugElement *elem1 = a;
+	const SimDebugElement *elem2 = b;
+
+	if (elem1->hash == elem2->hash) {
+		return 0;
+	}
+	return 1;
+}
+
+static void debug_element_free(void *val)
+{
+	SimDebugElement *elem = val;
+	MEM_freeN(elem);
+}
+
+SimDebugData *BKE_sim_debug_data_new(void)
+{
+	SimDebugData *debug_data = MEM_callocN(sizeof(SimDebugData), "sim debug data");
+	debug_data->gh = BLI_ghash_new(debug_element_hash, debug_element_compare, "sim debug element hash");
+	return debug_data;
+	
+}
+
+static void debug_data_insert(SimDebugData *debug_data, SimDebugElement *elem)
+{
+	SimDebugElement *old_elem = BLI_ghash_lookup(debug_data->gh, elem);
+	if (old_elem) {
+		*old_elem = *elem;
+		MEM_freeN(elem);
+	}
+	else
+		BLI_ghash_insert(debug_data->gh, elem, elem);
+}
+
+void BKE_sim_debug_data_add_dot(struct SimDebugData *debug_data, const float p[3], float r, float g, float b, int hash)
+{
+	SimDebugElement *elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
+	elem->type = SIM_DEBUG_ELEM_DOT;
+	elem->hash = hash;
+	elem->color[0] = r;
+	elem->color[1] = g;
+	elem->color[2] = b;
+	copy_v3_v3(elem->v1, p);
+	
+	debug_data_insert(debug_data, elem);
+}
+
+void BKE_sim_debug_data_add_line(struct SimDebugData *debug_data, const float p1[3], const float p2[3], float r, float g, float b, int hash)
+{
+	SimDebugElement *elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
+	elem->type = SIM_DEBUG_ELEM_LINE;
+	elem->hash = hash;
+	elem->color[0] = r;
+	elem->color[1] = g;
+	elem->color[2] = b;
+	copy_v3_v3(elem->v1, p1);
+	copy_v3_v3(elem->v2, p2);
+	
+	debug_data_insert(debug_data, elem);
+}
+
+void BKE_sim_debug_data_add_vector(struct SimDebugData *debug_data, const float p[3], const float d[3], float r, float g, float b, int hash)
+{
+	SimDebugElement *elem = MEM_callocN(sizeof(SimDebugElement), "sim debug data element");
+	elem->type = SIM_DEBUG_ELEM_VECTOR;
+	elem->hash = hash;
+	elem->color[0] = r;
+	elem->color[1] = g;
+	elem->color[2] = b;
+	copy_v3_v3(elem->v1, p);
+	copy_v3_v3(elem->v2, d);
+	
+	debug_data_insert(debug_data, elem);
+}
+
+void BKE_sim_debug_data_clear(SimDebugData *debug_data)
+{
+	if (!debug_data)
+		return;
+	
+	if (debug_data->gh)
+		BLI_ghash_clear(debug_data->gh, NULL, debug_element_free);
+}
+
+void BKE_sim_debug_data_free(SimDebugData *debug_data)
+{
+	if (!debug_data)
+		return;
+	
+	if (debug_data->gh)
+		BLI_ghash_free(debug_data->gh, NULL, debug_element_free);
+	MEM_freeN(debug_data);
+}
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);