[Bf-blender-cvs] [ef8c8a8] strand_gpu: Modified the guide strand creation operator to allow shorter-than-max strands.

[Lukas Tönne]

Commit: ef8c8a8b665b50ee41b7310d15383c7353ca1292
Author: Lukas Tönne
Date:   Sat Jul 2 14:16:46 2016 +0200
Branches: strand_gpu
https://developer.blender.org/rBef8c8a8b665b50ee41b7310d15383c7353ca1292

Modified the guide strand creation operator to allow shorter-than-max strands.

The guide strand format may change, but it should allow varying numbers of control
points.

===================================================================

M	source/blender/blenkernel/intern/strands.c
M	source/blender/gpu/intern/gpu_buffers.c

===================================================================

diff --git a/source/blender/blenkernel/intern/strands.c b/source/blender/blenkernel/intern/strands.c
index 0489831..53ed820 100644
--- a/source/blender/blenkernel/intern/strands.c
+++ b/source/blender/blenkernel/intern/strands.c
@@ -35,6 +35,7 @@
 
 #include "BLI_kdtree.h"
 #include "BLI_math.h"
+#include "BLI_rand.h"
 
 #include "BKE_DerivedMesh.h"
 #include "BKE_mesh_sample.h"
@@ -153,29 +154,24 @@ void BKE_strands_test_init(struct Strands *strands, struct DerivedMesh *scalp,
                            int totcurves, int maxverts,
                            unsigned int seed)
 {
-	const unsigned int totverts = totcurves * maxverts;
+	unsigned int seed2 = seed ^ 0xdeadbeef;
+	RNG *rng = BLI_rng_new(seed2);
 	
 	MeshSampleGenerator *gen = BKE_mesh_sample_gen_surface_random(scalp, seed);
 	unsigned int i, k;
 	
+	/* First generate all curves, to define vertex counts */
 	StrandCurve *curves = MEM_mallocN(sizeof(StrandCurve) * totcurves, "StrandCurve buffer");
-	StrandVertex *verts = MEM_mallocN(sizeof(StrandVertex) * totverts, "StrandVertex buffer");
-	
 	StrandCurve *c = curves;
-	StrandVertex *v = verts;
-	unsigned int verts_begin = 0;
+	unsigned int totverts = 0;
 	for (i = 0; i < totcurves; ++i, ++c) {
+		int num_verts = (int)(BLI_rng_get_float(rng) * (float)(maxverts + 1));
+		CLAMP(num_verts, 2, maxverts);
+		
 		if (BKE_mesh_sample_generate(gen, &c->root)) {
-			c->verts_begin = verts_begin;
-			c->num_verts = maxverts;
-			
-			for (k = 0; k < c->num_verts; ++k, ++v) {
-				v->co[0] = 0.0f;
-				v->co[1] = 0.0f;
-				v->co[2] = (c->num_verts > 1) ? (float)k / (c->num_verts - 1) : 0.0f;
-			}
-			
-			verts_begin += c->num_verts;
+			c->verts_begin = totverts;
+			c->num_verts = num_verts;
+			totverts += num_verts;
 		}
 		else {
 			/* clear remaining samples */
@@ -184,6 +180,20 @@ void BKE_strands_test_init(struct Strands *strands, struct DerivedMesh *scalp,
 		}
 	}
 	
+	/* Now generate vertices */
+	float segment_length = (maxverts > 1) ? 1.0f / (maxverts - 1) : 0.0f;
+	
+	StrandVertex *verts = MEM_mallocN(sizeof(StrandVertex) * totverts, "StrandVertex buffer");
+	c = curves;
+	StrandVertex *v = verts;
+	for (i = 0; i < totcurves; ++i, ++c) {
+		for (k = 0; k < c->num_verts; ++k, ++v) {
+			v->co[0] = 0.0f;
+			v->co[1] = 0.0f;
+			v->co[2] = segment_length * k;
+		}
+	}
+	
 	BKE_mesh_sample_free_generator(gen);
 	
 	if (strands->curves)
@@ -194,6 +204,8 @@ void BKE_strands_test_init(struct Strands *strands, struct DerivedMesh *scalp,
 	strands->verts = verts;
 	strands->totcurves = totcurves;
 	strands->totverts = totverts;
+	
+	BLI_rng_free(rng);
 }
 
 static void strands_calc_weights(const Strands *strands, struct DerivedMesh *scalp, StrandRoot *roots, int num_roots)
diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index abe59d2..3728119 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -2193,6 +2193,7 @@ static void strands_copy_edge_buffer(StrandData *strands, unsigned int (*varray)
 	StrandCurveData *curve = strands->curves;
 	for (c = 0; c < totcurves; ++c, ++curve) {
 		int verts_begin = curve->verts_begin, num_verts = curve->num_verts, v;
+		BLI_assert(num_verts >= 2);
 		
 		StrandVertexData *vert = strands->verts + verts_begin;
 		for (v = 0; v < num_verts - 1; ++v, ++vert) {