1 files changed, 145 insertions, 0 deletions
diff --git a/intern/cycles/kernel/kernel_light.h b/intern/cycles/kernel/kernel_light.h
new file mode 100644
index 00000000000..537f7ea00f0
--- /dev/null
+++ b/intern/cycles/kernel/kernel_light.h
@@ -0,0 +1,145 @@
+/*
+ * Copyright 2011, Blender Foundation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+CCL_NAMESPACE_BEGIN
+
+struct LightSample {
+	float3 P;
+	float3 Ng;
+	int object;
+	int prim;
+	int shader;
+	float weight;
+};
+
+/* Point Light */
+
+__device void point_light_sample(KernelGlobals *kg, int point,
+	float randu, float randv, float3 P, LightSample *ls)
+{
+	float4 f = kernel_tex_fetch(__light_point, point);
+
+	ls->P = make_float3(f.x, f.y, f.z);
+	ls->Ng = normalize(ls->P - P);
+	ls->shader = __float_as_int(f.w);
+	ls->object = ~0;
+	ls->prim = ~0;
+}
+
+__device float point_light_pdf(KernelGlobals *kg, float t)
+{
+	return t*t*kernel_data.integrator.pdf_lights;
+}
+
+/* Triangle Light */
+
+__device void triangle_light_sample(KernelGlobals *kg, int prim, int object,
+	float randu, float randv, LightSample *ls)
+{
+	/* triangle, so get position, normal, shader */
+	ls->P = triangle_sample_MT(kg, prim, randu, randv);
+	ls->Ng = triangle_normal_MT(kg, prim, &ls->shader);
+	ls->object = object;
+	ls->prim = prim;
+
+#ifdef __INSTANCING__
+	/* instance transform */
+	if(ls->object >= 0) {
+		object_position_transform(kg, ls->object, &ls->P);
+		object_normal_transform(kg, ls->object, &ls->Ng);
+	}
+#endif
+}
+
+__device float triangle_light_pdf(KernelGlobals *kg,
+	const float3 Ng, const float3 I, float t)
+{
+	float cos_pi = fabsf(dot(Ng, I));
+
+	if(cos_pi == 0.0f)
+		return 0.0f;
+	
+	return (t*t*kernel_data.integrator.pdf_triangles)/cos_pi;
+}
+
+/* Light Distribution */
+
+__device int light_distribution_sample(KernelGlobals *kg, float randt)
+{
+	/* this is basically std::upper_bound as used by pbrt, to find a point light or
+	   triangle to emit from, proportional to area. a good improvement would be to
+	   also sample proportional to power, though it's not so well defined with
+	   OSL shaders. */
+	int first = 0;
+	int len = kernel_data.integrator.num_distribution + 1;
+
+	while(len > 0) {
+		int half_len = len >> 1;
+		int middle = first + half_len;
+
+		if(randt < kernel_tex_fetch(__light_distribution, middle).x) {
+			len = half_len;
+		}
+		else {
+			first = middle + 1;
+			len = len - half_len - 1;
+		}
+	}
+
+	first = max(0, first-1);
+	kernel_assert(first >= 0 && first < kernel_data.integrator.num_distribution);
+
+	return first;
+}
+
+/* Generic Light */
+
+__device void light_sample(KernelGlobals *kg, float randt, float randu, float randv, float3 P, LightSample *ls)
+{
+	/* sample index */
+	int index = light_distribution_sample(kg, randt);
+
+	/* fetch light data */
+	float4 l = kernel_tex_fetch(__light_distribution, index);
+	int prim = __float_as_int(l.y);
+	ls->weight = l.z;
+
+	if(prim >= 0) {
+		int object = __float_as_int(l.w);
+		triangle_light_sample(kg, prim, object, randu, randv, ls);
+	}
+	else {
+		int point = -prim-1;
+		point_light_sample(kg, point, randu, randv, P, ls);
+	}
+}
+
+__device float light_pdf(KernelGlobals *kg, LightSample *ls, float3 I, float t)
+{
+	float pdf;
+
+	if(ls->prim != ~0)
+		pdf = triangle_light_pdf(kg, ls->Ng, I, t);
+	else
+		pdf = point_light_pdf(kg, t);
+	
+	return pdf;
+}
+
+CCL_NAMESPACE_END
+