1 files changed, 118 insertions, 0 deletions
diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
new file mode 100644
index 00000000000..6b6033e9ebd
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+++ b/intern/cycles/kernel/kernel_emission.h
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+/*
+ * 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
+
+/* Direction Emission */
+
+__device float3 direct_emissive_eval(KernelGlobals *kg, float rando,
+	LightSample *ls, float u, float v, float3 I)
+{
+	/* setup shading at emitter */
+	ShaderData sd;
+
+	shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v);
+	ls->Ng = sd.Ng;
+
+	/* no path flag, we're evaluating this for all closures. that's weak but
+	   we'd have to do multiple evaluations otherwise */
+	shader_eval_surface(kg, &sd, rando, 0);
+	
+	float3 eval;
+
+	/* evaluate emissive closure */
+	if(sd.flag & SD_EMISSION)
+		eval = shader_emissive_eval(kg, &sd);
+	else
+		eval = make_float3(0.0f, 0.0f, 0.0f);
+
+	shader_release(kg, &sd);
+
+	return eval;
+}
+
+__device bool direct_emission(KernelGlobals *kg, ShaderData *sd, float randt, float rando,
+	float randu, float randv, Ray *ray, float3 *eval)
+{
+	/* sample a position on a light */
+	LightSample ls;
+
+	light_sample(kg, randt, randu, randv, sd->P, &ls);
+
+	/* compute incoming direction and distance */
+	float t;
+	float3 omega_in = normalize_len(ls.P - sd->P, &t);
+
+	/* compute pdf */
+	float pdf = light_pdf(kg, &ls, -omega_in, t);
+
+	/* evaluate closure */
+	*eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -omega_in);
+
+	if(is_zero(*eval) || pdf == 0.0f)
+		return false;
+
+	/* evaluate BSDF at shading point */
+	float bsdf_pdf;
+	float3 bsdf_eval = shader_bsdf_eval(kg, sd, omega_in, &bsdf_pdf);
+
+	*eval *= bsdf_eval/pdf;
+
+	if(is_zero(*eval))
+		return false;
+
+	if(ls.prim != ~0) {
+		/* multiple importance sampling */
+		float mis_weight = power_heuristic(pdf, bsdf_pdf);
+		*eval *= mis_weight;
+	}
+	else {
+		/* ensure point light works in Watts, this should be handled
+		 * elsewhere but for now together with the diffuse emission
+		 * closure it works out to the right value */
+		*eval *= 0.25f;
+	}
+
+	/* setup ray */
+	ray->P = ray_offset(sd->P, sd->Ng);
+	ray->D = ray_offset(ls.P, ls.Ng) - ray->P;
+	ray->D = normalize_len(ray->D, &ray->t);
+
+	return true;
+}
+
+/* Indirect Emission */
+
+__device float3 indirect_emission(KernelGlobals *kg, ShaderData *sd, float t, int path_flag, float bsdf_pdf)
+{
+	/* evaluate emissive closure */
+	float3 L = shader_emissive_eval(kg, sd);
+
+	if(!(path_flag & PATH_RAY_SINGULAR)) {
+		/* multiple importance sampling */
+		float pdf = triangle_light_pdf(kg, sd->Ng, sd->I, t);
+		float mis_weight = power_heuristic(bsdf_pdf, pdf);
+
+		return L*mis_weight;
+	}
+
+	return L;
+}
+
+CCL_NAMESPACE_END
+