Cycles: make multiple importance sampling for lamps an option per lamp now,

disabled by default for backwards compatibility.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Integrator

1 files changed, 26 insertions, 2 deletions

diff --git a/intern/cycles/render/light.cpp b/intern/cycles/render/light.cpp
index 04fea1953e7..e7fb9514371 100644
--- a/intern/cycles/render/light.cpp
+++ b/intern/cycles/render/light.cpp
@@ -115,6 +115,8 @@ Light::Light()
 	spot_smooth = 0.0f;
 
 	cast_shadow = true;
+	use_mis = false;
+
 	shader = 0;
 	samples = 1;
 }
@@ -291,13 +293,19 @@ void LightManager::device_update_distribution(Device *device, DeviceScene *dscen
 
 	/* point lights */
 	float lightarea = (totarea > 0.0f)? totarea/scene->lights.size(): 1.0f;
+	bool use_lamp_mis = false;
 
 	for(int i = 0; i < scene->lights.size(); i++, offset++) {
+		Light *light = scene->lights[i];
+
 		distribution[offset].x = totarea;
 		distribution[offset].y = __int_as_float(~(int)i);
 		distribution[offset].z = 1.0f;
-		distribution[offset].w = scene->lights[i]->size;
+		distribution[offset].w = light->size;
 		totarea += lightarea;
+
+		if(light->size > 0.0f && light->use_mis)
+			use_lamp_mis = true;
 	}
 
 	/* normalize cumulative distribution functions */
@@ -344,6 +352,8 @@ void LightManager::device_update_distribution(Device *device, DeviceScene *dscen
 			kintegrator->inv_pdf_lights = 1.0f/kintegrator->pdf_lights;
 		}
 
+		kintegrator->use_lamp_mis = use_lamp_mis;
+
 		/* CDF */
 		device->tex_alloc("__light_distribution", dscene->light_distribution);
 	}
@@ -355,6 +365,7 @@ void LightManager::device_update_distribution(Device *device, DeviceScene *dscen
 		kintegrator->pdf_triangles = 0.0f;
 		kintegrator->pdf_lights = 0.0f;
 		kintegrator->inv_pdf_lights = 0.0f;
+		kintegrator->use_lamp_mis = false;
 	}
 }
 
@@ -484,6 +495,9 @@ void LightManager::device_update_points(Device *device, DeviceScene *dscene, Sce
 			float radius = light->size;
 			float invarea = (radius > 0.0f)? 1.0f/(M_PI_F*radius*radius): 1.0f;
 
+			if(light->use_mis && radius > 0.0f)
+				shader_id |= SHADER_USE_MIS;
+
 			light_data[i*LIGHT_SIZE + 0] = make_float4(__int_as_float(light->type), co.x, co.y, co.z);
 			light_data[i*LIGHT_SIZE + 1] = make_float4(__int_as_float(shader_id), radius, invarea, 0.0f);
 			light_data[i*LIGHT_SIZE + 2] = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
@@ -498,6 +512,9 @@ void LightManager::device_update_points(Device *device, DeviceScene *dscene, Sce
 			float area = M_PI_F*radius*radius;
 			float invarea = (area > 0.0f)? 1.0f/area: 1.0f;
 
+			if(light->use_mis && area > 0.0f)
+				shader_id |= SHADER_USE_MIS;
+
 			light_data[i*LIGHT_SIZE + 0] = make_float4(__int_as_float(light->type), dir.x, dir.y, dir.z);
 			light_data[i*LIGHT_SIZE + 1] = make_float4(__int_as_float(shader_id), radius, cosangle, invarea);
 			light_data[i*LIGHT_SIZE + 2] = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
@@ -505,6 +522,7 @@ void LightManager::device_update_points(Device *device, DeviceScene *dscene, Sce
 		}
 		else if(light->type == LIGHT_BACKGROUND) {
 			shader_id &= ~SHADER_AREA_LIGHT;
+			shader_id |= SHADER_USE_MIS;
 
 			light_data[i*LIGHT_SIZE + 0] = make_float4(__int_as_float(light->type), 0.0f, 0.0f, 0.0f);
 			light_data[i*LIGHT_SIZE + 1] = make_float4(__int_as_float(shader_id), 0.0f, 0.0f, 0.0f);
@@ -515,7 +533,10 @@ void LightManager::device_update_points(Device *device, DeviceScene *dscene, Sce
 			float3 axisu = light->axisu*(light->sizeu*light->size);
 			float3 axisv = light->axisv*(light->sizev*light->size);
 			float area = len(axisu)*len(axisv);
-			float invarea = (area > 0.0f)? 1.0f/area: 0.0f;
+			float invarea = (area > 0.0f)? 1.0f/area: 1.0f;
+
+			if(light->use_mis && area > 0.0f)
+				shader_id |= SHADER_USE_MIS;
 
 			light_data[i*LIGHT_SIZE + 0] = make_float4(__int_as_float(light->type), co.x, co.y, co.z);
 			light_data[i*LIGHT_SIZE + 1] = make_float4(__int_as_float(shader_id), axisu.x, axisu.y, axisu.z);
@@ -530,6 +551,9 @@ void LightManager::device_update_points(Device *device, DeviceScene *dscene, Sce
 			float spot_angle = cosf(light->spot_angle*0.5f);
 			float spot_smooth = (1.0f - spot_angle)*light->spot_smooth;
 
+			if(light->use_mis && radius > 0.0f)
+				shader_id |= SHADER_USE_MIS;
+
 			light_data[i*LIGHT_SIZE + 0] = make_float4(__int_as_float(light->type), co.x, co.y, co.z);
 			light_data[i*LIGHT_SIZE + 1] = make_float4(__int_as_float(shader_id), radius, invarea, spot_angle);
 			light_data[i*LIGHT_SIZE + 2] = make_float4(spot_smooth, dir.x, dir.y, dir.z);