1 files changed, 241 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..d5d47b28d59
--- /dev/null
+++ b/intern/cycles/kernel/kernel_light.h
@@ -0,0 +1,241 @@
+/*
+ * 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
+
+typedef struct LightSample {
+	float3 P;
+	float3 D;
+	float3 Ng;
+	float t;
+	int object;
+	int prim;
+	int shader;
+} LightSample;
+
+/* Regular Light */
+
+__device float3 disk_light_sample(float3 v, float randu, float randv)
+{
+	float3 ru, rv;
+
+	make_orthonormals(v, &ru, &rv);
+	to_unit_disk(&randu, &randv);
+
+	return ru*randu + rv*randv;
+}
+
+__device float3 distant_light_sample(float3 D, float size, float randu, float randv)
+{
+	return normalize(D + disk_light_sample(D, randu, randv)*size);
+}
+
+__device float3 sphere_light_sample(float3 P, float3 center, float size, float randu, float randv)
+{
+	return disk_light_sample(normalize(P - center), randu, randv)*size;
+}
+
+__device float3 area_light_sample(float3 axisu, float3 axisv, float randu, float randv)
+{
+	randu = randu - 0.5f;
+	randv = randv - 0.5f;
+
+	return axisu*randu + axisv*randv;
+}
+
+__device void regular_light_sample(KernelGlobals *kg, int point,
+	float randu, float randv, float3 P, LightSample *ls)
+{
+	float4 data0 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 0);
+	float4 data1 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 1);
+
+	LightType type = (LightType)__float_as_int(data0.x);
+
+	if(type == LIGHT_DISTANT) {
+		/* distant light */
+		float3 D = make_float3(data0.y, data0.z, data0.w);
+		float size = data1.y;
+
+		if(size > 0.0f)
+			D = distant_light_sample(D, size, randu, randv);
+
+		ls->P = D;
+		ls->Ng = D;
+		ls->D = -D;
+		ls->t = FLT_MAX;
+	}
+	else {
+		ls->P = make_float3(data0.y, data0.z, data0.w);
+
+		if(type == LIGHT_POINT) {
+			float size = data1.y;
+
+			/* sphere light */
+			if(size > 0.0f)
+				ls->P += sphere_light_sample(P, ls->P, size, randu, randv);
+
+			ls->Ng = normalize(P - ls->P);
+		}
+		else {
+			/* area light */
+			float4 data2 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 2);
+			float4 data3 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 3);
+
+			float3 axisu = make_float3(data1.y, data1.z, data2.w);
+			float3 axisv = make_float3(data2.y, data2.z, data2.w);
+			float3 D = make_float3(data3.y, data3.z, data3.w);
+
+			ls->P += area_light_sample(axisu, axisv, randu, randv);
+			ls->Ng = D;
+		}
+
+		ls->t = 0.0f;
+	}
+
+	ls->shader = __float_as_int(data1.x);
+	ls->object = ~0;
+	ls->prim = ~0;
+}
+
+__device float regular_light_pdf(KernelGlobals *kg,
+	const float3 Ng, const float3 I, float t)
+{
+	float pdf = kernel_data.integrator.pdf_lights;
+
+	if(t == FLT_MAX)
+		return pdf;
+
+	float cos_pi = dot(Ng, I);
+
+	if(cos_pi <= 0.0f)
+		return 0.0f;
+
+	return t*t*pdf/cos_pi;
+}
+
+/* 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;
+	ls->t = 0.0f;
+
+#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);
+
+	if(prim >= 0) {
+		int object = __float_as_int(l.w);
+		triangle_light_sample(kg, prim, object, randu, randv, ls);
+	}
+	else {
+		int point = -prim-1;
+		regular_light_sample(kg, point, randu, randv, P, ls);
+	}
+
+	/* compute incoming direction and distance */
+	if(ls->t != FLT_MAX)
+		ls->D = normalize_len(ls->P - P, &ls->t);
+}
+
+__device float light_sample_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 = regular_light_pdf(kg, ls->Ng, I, t);
+	
+	return pdf;
+}
+
+__device void light_select(KernelGlobals *kg, int index, float randu, float randv, float3 P, LightSample *ls)
+{
+	regular_light_sample(kg, index, randu, randv, P, ls);
+}
+
+__device float light_select_pdf(KernelGlobals *kg, LightSample *ls, float3 I, float t)
+{
+	return regular_light_pdf(kg, ls->Ng, I, t);
+}
+
+CCL_NAMESPACE_END
+