Cycles: remove min bounces, modify RR to terminate less.

Differential Revision: https://developer.blender.org/D2766

8 files changed, 25 insertions, 39 deletions

diff --git a/intern/cycles/blender/addon/presets.py b/intern/cycles/blender/addon/presets.py
index 82c4ffc6e50..440221b8470 100644
--- a/intern/cycles/blender/addon/presets.py
+++ b/intern/cycles/blender/addon/presets.py
@@ -32,12 +32,10 @@ class AddPresetIntegrator(AddPresetBase, Operator):
 
     preset_values = [
         "cycles.max_bounces",
-        "cycles.min_bounces",
         "cycles.diffuse_bounces",
         "cycles.glossy_bounces",
         "cycles.transmission_bounces",
         "cycles.volume_bounces",
-        "cycles.transparent_min_bounces",
         "cycles.transparent_max_bounces",
         "cycles.use_transparent_shadows",
         "cycles.caustics_reflective",
diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index 68474529ed3..cb5b13f8d3a 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -311,14 +311,6 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
                 default=0.0,
                 )
 
-        cls.min_bounces = IntProperty(
-                name="Min Bounces",
-                description="Minimum number of bounces, setting this lower "
-                            "than the maximum enables probabilistic path "
-                            "termination (faster but noisier)",
-                min=0, max=1024,
-                default=3,
-                )
         cls.max_bounces = IntProperty(
                 name="Max Bounces",
                 description="Total maximum number of bounces",
@@ -351,15 +343,6 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
                 default=0,
                 )
 
-        cls.transparent_min_bounces = IntProperty(
-                name="Transparent Min Bounces",
-                description="Minimum number of transparent bounces, setting "
-                            "this lower than the maximum enables "
-                            "probabilistic path termination (faster but "
-                            "noisier)",
-                min=0, max=1024,
-                default=8,
-                )
         cls.transparent_max_bounces = IntProperty(
                 name="Transparent Max Bounces",
                 description="Maximum number of transparent bounces",
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 49beebe5ab4..45a77aa8c38 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -292,7 +292,6 @@ class CyclesRender_PT_light_paths(CyclesButtonsPanel, Panel):
         sub = col.column(align=True)
         sub.label("Transparency:")
         sub.prop(cscene, "transparent_max_bounces", text="Max")
-        sub.prop(cscene, "transparent_min_bounces", text="Min")
         sub.prop(cscene, "use_transparent_shadows", text="Shadows")
 
         col.separator()
@@ -306,7 +305,6 @@ class CyclesRender_PT_light_paths(CyclesButtonsPanel, Panel):
         sub = col.column(align=True)
         sub.label(text="Bounces:")
         sub.prop(cscene, "max_bounces", text="Max")
-        sub.prop(cscene, "min_bounces", text="Min")
 
         sub = col.column(align=True)
         sub.prop(cscene, "diffuse_bounces", text="Diffuse")
diff --git a/intern/cycles/blender/blender_sync.cpp b/intern/cycles/blender/blender_sync.cpp
index 3a00384458a..ddaa962f63d 100644
--- a/intern/cycles/blender/blender_sync.cpp
+++ b/intern/cycles/blender/blender_sync.cpp
@@ -234,7 +234,6 @@ void BlenderSync::sync_integrator()
 	Integrator *integrator = scene->integrator;
 	Integrator previntegrator = *integrator;
 
-	integrator->min_bounce = get_int(cscene, "min_bounces");
 	integrator->max_bounce = get_int(cscene, "max_bounces");
 
 	integrator->max_diffuse_bounce = get_int(cscene, "diffuse_bounces");
@@ -243,7 +242,6 @@ void BlenderSync::sync_integrator()
 	integrator->max_volume_bounce = get_int(cscene, "volume_bounces");
 
 	integrator->transparent_max_bounce = get_int(cscene, "transparent_max_bounces");
-	integrator->transparent_min_bounce = get_int(cscene, "transparent_min_bounces");
 	integrator->transparent_shadows = get_boolean(cscene, "use_transparent_shadows");
 
 	integrator->volume_max_steps = get_int(cscene, "volume_max_steps");
diff --git a/intern/cycles/kernel/kernel_path_state.h b/intern/cycles/kernel/kernel_path_state.h
index 5d92fd12201..a96ffe07718 100644
--- a/intern/cycles/kernel/kernel_path_state.h
+++ b/intern/cycles/kernel/kernel_path_state.h
@@ -163,14 +163,23 @@ ccl_device_inline uint path_state_ray_visibility(KernelGlobals *kg, PathState *s
 ccl_device_inline float path_state_terminate_probability(KernelGlobals *kg, ccl_addr_space PathState *state, const float3 throughput)
 {
 	if(state->flag & PATH_RAY_TRANSPARENT) {
-		/* transparent rays treated separately */
-		if(state->transparent_bounce >= kernel_data.integrator.transparent_max_bounce)
+		/* Transparent rays are treated separately with own max bounces. */
+		if(state->transparent_bounce >= kernel_data.integrator.transparent_max_bounce) {
 			return 0.0f;
-		else if(state->transparent_bounce <= kernel_data.integrator.transparent_min_bounce)
+		}
+		/* Do at least one bounce without RR. */
+		else if(state->transparent_bounce <= 1) {
 			return 1.0f;
+		}
+#ifdef __SHADOW_TRICKS__
+		/* Exception for shadow catcher not working correctly with RR. */
+		else if ((state->flag & PATH_RAY_SHADOW_CATCHER) && (state->transparent_bounce <= 8)) {
+			return 1.0f;
+		}
+#endif
 	}
 	else {
-		/* other rays */
+		/* Test max bounces for various ray types. */
 		if((state->bounce >= kernel_data.integrator.max_bounce) ||
 		   (state->diffuse_bounce >= kernel_data.integrator.max_diffuse_bounce) ||
 		   (state->glossy_bounce >= kernel_data.integrator.max_glossy_bounce) ||
@@ -181,13 +190,21 @@ ccl_device_inline float path_state_terminate_probability(KernelGlobals *kg, ccl_
 		{
 			return 0.0f;
 		}
-		else if(state->bounce <= kernel_data.integrator.min_bounce) {
+		/* Do at least one bounce without RR. */
+		else if(state->bounce <= 1) {
 			return 1.0f;
 		}
+#ifdef __SHADOW_TRICKS__
+		/* Exception for shadow catcher not working correctly with RR. */
+		else if ((state->flag & PATH_RAY_SHADOW_CATCHER) && (state->bounce <= 3)) {
+			return 1.0f;
+		}
+#endif
 	}
 
-	/* probalistic termination */
-	return average(throughput); /* todo: try using max here */
+	/* Probalistic termination: use sqrt() to roughly match typical view
+	 * transform and do path termination a bit later on average. */
+	return sqrtf(max3(fabs(throughput)));
 }
 
 /* TODO(DingTo): Find more meaningful name for this */
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index e6a62c42a38..557ce5804f8 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -1236,7 +1236,6 @@ typedef struct KernelIntegrator {
 	int portal_offset;
 
 	/* bounces */
-	int min_bounce;
 	int max_bounce;
 
 	int max_diffuse_bounce;
@@ -1247,7 +1246,6 @@ typedef struct KernelIntegrator {
 	int ao_bounces;
 
 	/* transparent */
-	int transparent_min_bounce;
 	int transparent_max_bounce;
 	int transparent_shadows;
 
@@ -1290,7 +1288,7 @@ typedef struct KernelIntegrator {
 	float light_inv_rr_threshold;
 
 	int start_sample;
-	int pad1, pad2, pad3;
+	int pad1;
 } KernelIntegrator;
 static_assert_align(KernelIntegrator, 16);
 
diff --git a/intern/cycles/render/integrator.cpp b/intern/cycles/render/integrator.cpp
index a004bb5b856..b9b8c681a26 100644
--- a/intern/cycles/render/integrator.cpp
+++ b/intern/cycles/render/integrator.cpp
@@ -31,7 +31,6 @@ NODE_DEFINE(Integrator)
 {
 	NodeType *type = NodeType::add("integrator", create);
 
-	SOCKET_INT(min_bounce, "Min Bounce", 2);
 	SOCKET_INT(max_bounce, "Max Bounce", 7);
 
 	SOCKET_INT(max_diffuse_bounce, "Max Diffuse Bounce", 7);
@@ -39,7 +38,6 @@ NODE_DEFINE(Integrator)
 	SOCKET_INT(max_transmission_bounce, "Max Transmission Bounce", 7);
 	SOCKET_INT(max_volume_bounce, "Max Volume Bounce", 7);
 
-	SOCKET_INT(transparent_min_bounce, "Transparent Min Bounce", 2);
 	SOCKET_INT(transparent_max_bounce, "Transparent Max Bounce", 7);
 	SOCKET_BOOLEAN(transparent_shadows, "Transparent Shadows", false);
 
@@ -104,7 +102,6 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
 
 	/* integrator parameters */
 	kintegrator->max_bounce = max_bounce + 1;
-	kintegrator->min_bounce = min_bounce + 1;
 
 	kintegrator->max_diffuse_bounce = max_diffuse_bounce + 1;
 	kintegrator->max_glossy_bounce = max_glossy_bounce + 1;
@@ -112,7 +109,6 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
 	kintegrator->max_volume_bounce = max_volume_bounce + 1;
 
 	kintegrator->transparent_max_bounce = transparent_max_bounce + 1;
-	kintegrator->transparent_min_bounce = transparent_min_bounce + 1;
 
 	if(ao_bounces == 0) {
 		kintegrator->ao_bounces = INT_MAX;
diff --git a/intern/cycles/render/integrator.h b/intern/cycles/render/integrator.h
index 9501d7f8416..ce5651ec823 100644
--- a/intern/cycles/render/integrator.h
+++ b/intern/cycles/render/integrator.h
@@ -31,7 +31,6 @@ class Integrator : public Node {
 public:
 	NODE_DECLARE
 
-	int min_bounce;
 	int max_bounce;
 
 	int max_diffuse_bounce;
@@ -39,7 +38,6 @@ public:
 	int max_transmission_bounce;
 	int max_volume_bounce;
 
-	int transparent_min_bounce;
 	int transparent_max_bounce;
 	bool transparent_shadows;