1 files changed, 63 insertions, 1 deletions

diff --git a/intern/cycles/kernel/kernel_light.h b/intern/cycles/kernel/kernel_light.h
index 97ae2d3db87..0f74ab75dd4 100644
--- a/intern/cycles/kernel/kernel_light.h
+++ b/intern/cycles/kernel/kernel_light.h
@@ -326,6 +326,59 @@ __device float triangle_light_pdf(KernelGlobals *kg,
 	return (t*t*kernel_data.integrator.pdf_triangles)/cos_pi;
 }
 
+#ifdef __HAIR__
+/* Strand Light */
+
+__device void curve_seg_light_sample(KernelGlobals *kg, int prim, int object,
+	float randu, float randv, float time, LightSample *ls)
+{
+	/* this strand code needs completion */
+	float4 v00 = kernel_tex_fetch(__cur_segs, prim);
+
+	int v1 = __float_as_int(v00.x);
+	int v2 = __float_as_int(v00.y);
+	float l = v00.w;
+
+	float4 P1 = kernel_tex_fetch(__cur_keys, v1);
+	float4 P2 = kernel_tex_fetch(__cur_keys, v2);
+	float r1 = P1.w;
+	float r2 = P2.w;
+	float3 tg = float4_to_float3(P2 - P1) / l;
+	float3 xc = make_float3(tg.x * tg.z, tg.y * tg.z, -(tg.x * tg.x + tg.y * tg.y));
+	if (dot(xc, xc) == 0.0f)
+		xc = make_float3(tg.x * tg.y, -(tg.x * tg.x + tg.z * tg.z), tg.z * tg.y);
+	xc = normalize(xc);
+	float3 yc = cross(tg, xc);
+	float gd = ((r2 - r1)/l);
+
+	/* normal currently ignores gradient */
+	ls->Ng = sinf(2 * M_PI_F * randv) * xc + cosf(2 * M_PI_F * randv) * yc;
+	ls->P = randu * l * tg + (gd * l + r1) * ls->Ng;
+	ls->object = object;
+	ls->prim = prim;
+	ls->t = 0.0f;
+	ls->type = LIGHT_STRAND;
+	ls->eval_fac = 1.0f;
+	ls->shader = __float_as_int(v00.z);
+
+#ifdef __INSTANCING__
+	/* instance transform */
+	if(ls->object >= 0) {
+#ifdef __OBJECT_MOTION__
+		Transform itfm;
+		Transform tfm = object_fetch_transform_motion_test(kg, object, time, &itfm);
+#else
+		Transform tfm = object_fetch_transform(kg, ls->object, OBJECT_TRANSFORM);
+		Transform itfm = object_fetch_transform(kg, ls->object, OBJECT_INVERSE_TRANSFORM);
+#endif
+
+		ls->P = transform_point(&tfm, ls->P);
+		ls->Ng = normalize(transform_direction(&tfm, ls->Ng));
+	}
+#endif
+}
+#endif
+
 /* Light Distribution */
 
 __device int light_distribution_sample(KernelGlobals *kg, float randt)
@@ -365,10 +418,19 @@ __device void light_sample(KernelGlobals *kg, float randt, float randu, float ra
 	/* fetch light data */
 	float4 l = kernel_tex_fetch(__light_distribution, index);
 	int prim = __float_as_int(l.y);
+#ifdef __HAIR__
+/* currently use l.z to indicate is strand sample which isn't ideal */
+	bool is_curve = __float_as_int(l.z) == 0.0f;
+#endif
 
 	if(prim >= 0) {
 		int object = __float_as_int(l.w);
-		triangle_light_sample(kg, prim, object, randu, randv, time, ls);
+#ifdef __HAIR__
+		if (is_curve)
+			curve_seg_light_sample(kg, prim, object, randu, randv, time, ls);
+		else
+#endif
+			triangle_light_sample(kg, prim, object, randu, randv, time, ls);
 	}
 	else {
 		int point = -prim-1;