Cycles: constant folding for RGB/Vector Curves and Color Ramp.

These are complex nodes, and it's conceivable they may end up constant
in some circumstances within node groups, so folding support is useful.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2084

11 files changed, 279 insertions, 135 deletions

diff --git a/intern/cycles/kernel/CMakeLists.txt b/intern/cycles/kernel/CMakeLists.txt
index 685574eb394..0d663bb474f 100644
--- a/intern/cycles/kernel/CMakeLists.txt
+++ b/intern/cycles/kernel/CMakeLists.txt
@@ -140,6 +140,7 @@ set(SRC_SVM_HEADERS
 	svm/svm_noisetex.h
 	svm/svm_normal.h
 	svm/svm_ramp.h
+	svm/svm_ramp_util.h
 	svm/svm_sepcomb_hsv.h
 	svm/svm_sepcomb_vector.h
 	svm/svm_sky.h
diff --git a/intern/cycles/kernel/shaders/node_ramp_util.h b/intern/cycles/kernel/shaders/node_ramp_util.h
new file mode 100644
index 00000000000..917fb65c6df
--- /dev/null
+++ b/intern/cycles/kernel/shaders/node_ramp_util.h
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2011-2013 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* NOTE: svm_ramp.h, svm_ramp_util.h and node_ramp_util.h must stay consistent */
+
+color rgb_ramp_lookup(color ramp[], float at, int interpolate, int extrapolate)
+{
+	float f = at;
+	int table_size = arraylength(ramp);
+
+	if ((f < 0.0 || f > 1.0) && extrapolate) {
+		color t0, dy;
+		if (f < 0.0) {
+			t0 = ramp[0];
+			dy = t0 - ramp[1];
+			f = -f;
+		}
+		else {
+			t0 = ramp[table_size - 1];
+			dy = t0 - ramp[table_size - 2];
+			f = f - 1.0;
+		}
+		return t0 + dy * f * (table_size - 1);
+	}
+
+	f = clamp(at, 0.0, 1.0) * (table_size - 1);
+
+	/* clamp int as well in case of NaN */
+	int i = (int)f;
+	if (i < 0) i = 0;
+	if (i >= table_size) i = table_size - 1;
+	float t = f - (float)i;
+
+	color result = ramp[i];
+
+	if (interpolate && t > 0.0)
+		result = (1.0 - t) * result + t * ramp[i + 1];
+
+	return result;
+}
+
+float rgb_ramp_lookup(float ramp[], float at, int interpolate, int extrapolate)
+{
+	float f = at;
+	int table_size = arraylength(ramp);
+
+	if ((f < 0.0 || f > 1.0) && extrapolate) {
+		float t0, dy;
+		if (f < 0.0) {
+			t0 = ramp[0];
+			dy = t0 - ramp[1];
+			f = -f;
+		}
+		else {
+			t0 = ramp[table_size - 1];
+			dy = t0 - ramp[table_size - 2];
+			f = f - 1.0;
+		}
+		return t0 + dy * f * (table_size - 1);
+	}
+
+	f = clamp(at, 0.0, 1.0) * (table_size - 1);
+
+	/* clamp int as well in case of NaN */
+	int i = (int)f;
+	if (i < 0) i = 0;
+	if (i >= table_size) i = table_size - 1;
+	float t = f - (float)i;
+
+	float result = ramp[i];
+
+	if (interpolate && t > 0.0)
+		result = (1.0 - t) * result + t * ramp[i + 1];
+	
+	return result;
+}
diff --git a/intern/cycles/kernel/shaders/node_rgb_curves.osl b/intern/cycles/kernel/shaders/node_rgb_curves.osl
index 8e208e8a8f7..c8e7e4f175b 100644
--- a/intern/cycles/kernel/shaders/node_rgb_curves.osl
+++ b/intern/cycles/kernel/shaders/node_rgb_curves.osl
@@ -14,43 +14,7 @@
  * limitations under the License.
  */
 
-#include "stdosl.h"
-#include "oslutil.h"
-
-float ramp_lookup(color ramp[], float at, int component)
-{
-	int table_size = arraylength(ramp);
-
-	if (at < 0.0 || at > 1.0) {
-		float t0, dy;
-		if (at < 0.0) {
-			t0 = ramp[0][component];
-			dy = t0 - ramp[1][component];
-			at = -at;
-		}
-		else {
-			t0 = ramp[table_size - 1][component];
-			dy = t0 - ramp[table_size - 2][component];
-			at = at - 1.0;
-		}
-		return t0 + dy * at * (table_size - 1);
-	}
-
-	float f = clamp(at, 0.0, 1.0) * (table_size - 1);
-
-	/* clamp int as well in case of NaN */
-	int i = (int)f;
-	if (i < 0) i = 0;
-	if (i >= table_size) i = table_size - 1;
-	float t = f - (float)i;
-
-	float result = ramp[i][component];
-
-	if (t > 0.0)
-		result = (1.0 - t) * result + t * ramp[i + 1][component];
-	
-	return result;
-}
+#include "node_ramp_util.h"
 
 shader node_rgb_curves(
 	color ramp[] = {0.0},
@@ -63,9 +27,13 @@ shader node_rgb_curves(
 {
 	color c = (ColorIn - color(min_x, min_x, min_x)) / (max_x - min_x);
 
-	ColorOut[0] = ramp_lookup(ramp, c[0], 0);
-	ColorOut[1] = ramp_lookup(ramp, c[1], 1);
-	ColorOut[2] = ramp_lookup(ramp, c[2], 2);
+	color r = rgb_ramp_lookup(ramp, c[0], 1, 1);
+	color g = rgb_ramp_lookup(ramp, c[0], 1, 1);
+	color b = rgb_ramp_lookup(ramp, c[0], 1, 1);
+
+	ColorOut[0] = r[0];
+	ColorOut[1] = g[1];
+	ColorOut[2] = b[2];
 
 	ColorOut = mix(ColorIn, ColorOut, Fac);
 }
diff --git a/intern/cycles/kernel/shaders/node_rgb_ramp.osl b/intern/cycles/kernel/shaders/node_rgb_ramp.osl
index c0ae74d6b33..24b8728b999 100644
--- a/intern/cycles/kernel/shaders/node_rgb_ramp.osl
+++ b/intern/cycles/kernel/shaders/node_rgb_ramp.osl
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#include "stdosl.h"
-#include "oslutil.h"
+#include "node_ramp_util.h"
 
 shader node_rgb_ramp(
 	color ramp_color[] = {0.0},
@@ -26,21 +25,7 @@ shader node_rgb_ramp(
 	output color Color = 0.0,
 	output float Alpha = 1.0)
 {
-	int table_size = arraylength(ramp_color);
-	float f = clamp(Fac, 0.0, 1.0) * (table_size - 1);
-
-	/* clamp int as well in case of NaN */
-	int i = (int)f;
-	if (i < 0) i = 0;
-	if (i >= table_size) i = table_size - 1;
-	float t = f - (float)i;
-
-	Color = ramp_color[i];
-	Alpha = ramp_alpha[i];
-
-	if (interpolate && t > 0.0) {
-		Color = (1.0 - t) * Color + t * ramp_color[i + 1];
-		Alpha = (1.0 - t) * Alpha + t * ramp_alpha[i + 1];
-	}
+	Color = rgb_ramp_lookup(ramp_color, Fac, interpolate, 0);
+	Alpha = rgb_ramp_lookup(ramp_alpha, Fac, interpolate, 0);
 }
 
diff --git a/intern/cycles/kernel/shaders/node_vector_curves.osl b/intern/cycles/kernel/shaders/node_vector_curves.osl
index cff4efe1d98..d92fa11d439 100644
--- a/intern/cycles/kernel/shaders/node_vector_curves.osl
+++ b/intern/cycles/kernel/shaders/node_vector_curves.osl
@@ -14,43 +14,7 @@
  * limitations under the License.
  */
 
-#include "stdosl.h"
-#include "oslutil.h"
-
-float ramp_lookup(color ramp[], float at, int component)
-{
-	int table_size = arraylength(ramp);
-
-	if (at < 0.0 || at > 1.0) {
-		float t0, dy;
-		if (at < 0.0) {
-			t0 = ramp[0][component];
-			dy = t0 - ramp[1][component];
-			at = -at;
-		}
-		else {
-			t0 = ramp[table_size - 1][component];
-			dy = t0 - ramp[table_size - 2][component];
-			at = at - 1.0;
-		}
-		return t0 + dy * at * (table_size - 1);
-	}
-
-	float f = clamp(at, 0.0, 1.0) * (table_size - 1);
-
-	/* clamp int as well in case of NaN */
-	int i = (int)f;
-	if (i < 0) i = 0;
-	if (i >= table_size) i = table_size - 1;
-	float t = f - (float)i;
-
-	float result = ramp[i][component];
-
-	if (t > 0.0)
-		result = (1.0 - t) * result + t * ramp[i + 1][component];
-	
-	return result;
-}
+#include "node_ramp_util.h"
 
 shader node_vector_curves(
 	color ramp[] = {0.0},
@@ -63,9 +27,13 @@ shader node_vector_curves(
 {
 	vector c = (VectorIn - vector(min_x, min_x, min_x)) / (max_x - min_x);
 
-	VectorOut[0] = ramp_lookup(ramp, c[0], 0);
-	VectorOut[1] = ramp_lookup(ramp, c[1], 1);
-	VectorOut[2] = ramp_lookup(ramp, c[2], 2);
+	color r = rgb_ramp_lookup(ramp, c[0], 1, 1);
+	color g = rgb_ramp_lookup(ramp, c[0], 1, 1);
+	color b = rgb_ramp_lookup(ramp, c[0], 1, 1);
+
+	VectorOut[0] = r[0];
+	VectorOut[1] = g[1];
+	VectorOut[2] = b[2];
 
 	VectorOut = mix(VectorIn, VectorOut, Fac);
 }
diff --git a/intern/cycles/kernel/svm/svm.h b/intern/cycles/kernel/svm/svm.h
index de7e03e5a19..502994e71f1 100644
--- a/intern/cycles/kernel/svm/svm.h
+++ b/intern/cycles/kernel/svm/svm.h
@@ -405,10 +405,8 @@ ccl_device_noinline void svm_eval_nodes(KernelGlobals *kg, ShaderData *sd, ccl_a
 
 #if NODES_GROUP(NODE_GROUP_LEVEL_3)
 			case NODE_RGB_CURVES:
-				svm_node_rgb_curves(kg, sd, stack, node, &offset);
-				break;
 			case NODE_VECTOR_CURVES:
-				svm_node_vector_curves(kg, sd, stack, node, &offset);
+				svm_node_curves(kg, sd, stack, node, &offset);
 				break;
 			case NODE_TANGENT:
 				svm_node_tangent(kg, sd, stack, node);
diff --git a/intern/cycles/kernel/svm/svm_ramp.h b/intern/cycles/kernel/svm/svm_ramp.h
index 24275d05c4a..f959d90f309 100644
--- a/intern/cycles/kernel/svm/svm_ramp.h
+++ b/intern/cycles/kernel/svm/svm_ramp.h
@@ -19,6 +19,8 @@
 
 CCL_NAMESPACE_BEGIN
 
+/* NOTE: svm_ramp.h, svm_ramp_util.h and node_ramp_util.h must stay consistent */
+
 ccl_device float4 rgb_ramp_lookup(KernelGlobals *kg,
                                   int offset,
                                   float f,
@@ -75,36 +77,7 @@ ccl_device void svm_node_rgb_ramp(KernelGlobals *kg, ShaderData *sd, float *stac
 	*offset += table_size;
 }
 
-ccl_device void svm_node_rgb_curves(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
-{
-	uint fac_offset, color_offset, out_offset;
-	decode_node_uchar4(node.y,
-	                   &fac_offset,
-	                   &color_offset,
-	                   &out_offset,
-	                   NULL);
-
-	uint table_size = read_node(kg, offset).x;
-
-	float fac = stack_load_float(stack, fac_offset);
-	float3 color = stack_load_float3(stack, color_offset);
-
-	const float min_x = __int_as_float(node.z),
-	            max_x = __int_as_float(node.w);
-	const float range_x = max_x - min_x;
-	const float3 relpos = (color - make_float3(min_x, min_x, min_x)) / range_x;
-
-	float r = rgb_ramp_lookup(kg, *offset, relpos.x, true, true, table_size).x;
-	float g = rgb_ramp_lookup(kg, *offset, relpos.y, true, true, table_size).y;
-	float b = rgb_ramp_lookup(kg, *offset, relpos.z, true, true, table_size).z;
-
-	color = (1.0f - fac)*color + fac*make_float3(r, g, b);
-	stack_store_float3(stack, out_offset, color);
-
-	*offset += table_size;
-}
-
-ccl_device void svm_node_vector_curves(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
+ccl_device void svm_node_curves(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
 {
 	uint fac_offset, color_offset, out_offset;
 	decode_node_uchar4(node.y,
diff --git a/intern/cycles/kernel/svm/svm_ramp_util.h b/intern/cycles/kernel/svm/svm_ramp_util.h
new file mode 100644
index 00000000000..495d98cf250
--- /dev/null
+++ b/intern/cycles/kernel/svm/svm_ramp_util.h
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2011-2013 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __SVM_RAMP_UTIL_H__
+#define __SVM_RAMP_UTIL_H__
+
+CCL_NAMESPACE_BEGIN
+
+/* NOTE: svm_ramp.h, svm_ramp_util.h and node_ramp_util.h must stay consistent */
+
+ccl_device float3 rgb_ramp_lookup(const float3 *ramp,
+                                  float f,
+                                  bool interpolate,
+                                  bool extrapolate,
+                                  int table_size)
+{
+	if ((f < 0.0f || f > 1.0f) && extrapolate) {
+		float3 t0, dy;
+		if (f < 0.0f) {
+			t0 = ramp[0];
+			dy = t0 - ramp[1],
+			f = -f;
+		}
+		else {
+			t0 = ramp[table_size - 1];
+			dy = t0 - ramp[table_size - 2];
+			f = f - 1.0f;
+		}
+		return t0 + dy * f * (table_size - 1);
+	}
+
+	f = clamp(f, 0.0f, 1.0f) * (table_size - 1);
+
+	/* clamp int as well in case of NaN */
+	int i = clamp(float_to_int(f), 0, table_size-1);
+	float t = f - (float)i;
+
+	float3 result = ramp[i];
+
+	if (interpolate && t > 0.0f)
+		result = (1.0f - t) * result + t * ramp[i + 1];
+
+	return result;
+}
+
+ccl_device float float_ramp_lookup(const float *ramp,
+                                   float f,
+                                   bool interpolate,
+                                   bool extrapolate,
+                                   int table_size)
+{
+	if ((f < 0.0f || f > 1.0f) && extrapolate) {
+		float t0, dy;
+		if (f < 0.0f) {
+			t0 = ramp[0];
+			dy = t0 - ramp[1],
+			f = -f;
+		}
+		else {
+			t0 = ramp[table_size - 1];
+			dy = t0 - ramp[table_size - 2];
+			f = f - 1.0f;
+		}
+		return t0 + dy * f * (table_size - 1);
+	}
+
+	f = clamp(f, 0.0f, 1.0f) * (table_size - 1);
+
+	/* clamp int as well in case of NaN */
+	int i = clamp(float_to_int(f), 0, table_size-1);
+	float t = f - (float)i;
+
+	float result = ramp[i];
+
+	if (interpolate && t > 0.0f)
+		result = (1.0f - t) * result + t * ramp[i + 1];
+
+	return result;
+}
+
+CCL_NAMESPACE_END
+
+#endif /* __SVM_RAMP_UTIL_H__ */
+
diff --git a/intern/cycles/render/constant_fold.h b/intern/cycles/render/constant_fold.h
index 978c8e5335a..195e5b127e8 100644
--- a/intern/cycles/render/constant_fold.h
+++ b/intern/cycles/render/constant_fold.h
@@ -18,6 +18,7 @@
 #define __CONSTANT_FOLD_H__
 
 #include "util_types.h"
+#include "util_vector.h"
 
 CCL_NAMESPACE_BEGIN
 
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index 3af6a713290..b3b010841e9 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -20,6 +20,7 @@
 #include "scene.h"
 #include "svm.h"
 #include "svm_color_util.h"
+#include "svm_ramp_util.h"
 #include "svm_math_util.h"
 #include "osl.h"
 #include "constant_fold.h"
@@ -4855,6 +4856,30 @@ CurvesNode::CurvesNode(const NodeType *node_type)
 {
 }
 
+void CurvesNode::constant_fold(const ConstantFolder& folder, ShaderInput *value_in)
+{
+	ShaderInput *fac_in = input("Fac");
+
+	/* remove no-op node */
+	if(!fac_in->link && fac == 0.0f) {
+		folder.bypass(value_in->link);
+	}
+	/* evaluate fully constant node */
+	else if(folder.all_inputs_constant()) {
+		if (curves.size() == 0)
+			return;
+
+		float3 pos = (value - make_float3(min_x, min_x, min_x)) / (max_x - min_x);
+		float3 result;
+
+		result[0] = rgb_ramp_lookup(curves.data(), pos[0], true, true, curves.size()).x;
+		result[1] = rgb_ramp_lookup(curves.data(), pos[1], true, true, curves.size()).y;
+		result[2] = rgb_ramp_lookup(curves.data(), pos[2], true, true, curves.size()).z;
+
+		folder.make_constant(interp(value, result, fac));
+	}
+}
+
 void CurvesNode::compile(SVMCompiler& compiler, int type, ShaderInput *value_in, ShaderOutput *value_out)
 {
 	if(curves.size() == 0)
@@ -4918,6 +4943,11 @@ RGBCurvesNode::RGBCurvesNode()
 {
 }
 
+void RGBCurvesNode::constant_fold(const ConstantFolder& folder)
+{
+	CurvesNode::constant_fold(folder, input("Color"));
+}
+
 void RGBCurvesNode::compile(SVMCompiler& compiler)
 {
 	CurvesNode::compile(compiler, NODE_RGB_CURVES, input("Color"), output("Color"));
@@ -4951,6 +4981,11 @@ VectorCurvesNode::VectorCurvesNode()
 {
 }
 
+void VectorCurvesNode::constant_fold(const ConstantFolder& folder)
+{
+	CurvesNode::constant_fold(folder, input("Vector"));
+}
+
 void VectorCurvesNode::compile(SVMCompiler& compiler)
 {
 	CurvesNode::compile(compiler, NODE_VECTOR_CURVES, input("Vector"), output("Vector"));
@@ -4984,6 +5019,31 @@ RGBRampNode::RGBRampNode()
 {
 }
 
+void RGBRampNode::constant_fold(const ConstantFolder& folder)
+{
+	if(ramp.size() == 0 || ramp.size() != ramp_alpha.size())
+		return;
+
+	if(folder.all_inputs_constant()) {
+		float f = clamp(fac, 0.0f, 1.0f) * (ramp.size() - 1);
+
+		/* clamp int as well in case of NaN */
+		int i = clamp((int)f, 0, ramp.size()-1);
+		float t = f - (float)i;
+
+		bool use_lerp = interpolate && t > 0.0f;
+
+		if(folder.output == output("Color")) {
+			float3 color = rgb_ramp_lookup(ramp.data(), fac, use_lerp, false, ramp.size());
+			folder.make_constant(color);
+		}
+		else if(folder.output == output("Alpha")) {
+			float alpha = float_ramp_lookup(ramp_alpha.data(), fac, use_lerp, false, ramp_alpha.size());
+			folder.make_constant(alpha);
+		}
+	}
+}
+
 void RGBRampNode::compile(SVMCompiler& compiler)
 {
 	if(ramp.size() == 0 || ramp.size() != ramp_alpha.size())
diff --git a/intern/cycles/render/nodes.h b/intern/cycles/render/nodes.h
index 28b40ba756d..b0eb2395adf 100644
--- a/intern/cycles/render/nodes.h
+++ b/intern/cycles/render/nodes.h
@@ -889,28 +889,32 @@ public:
 
 	virtual int get_group() { return NODE_GROUP_LEVEL_3; }
 
-	bool has_spatial_varying() { return true; }
-	void compile(SVMCompiler& compiler, int type, ShaderInput *value_in, ShaderOutput *value_out);
-	void compile(OSLCompiler& compiler, const char *name);
-
 	array<float3> curves;
 	float min_x, max_x, fac;
 	float3 value;
+
+protected:
+	void constant_fold(const ConstantFolder& folder, ShaderInput *value_in);
+	void compile(SVMCompiler& compiler, int type, ShaderInput *value_in, ShaderOutput *value_out);
+	void compile(OSLCompiler& compiler, const char *name);
 };
 
 class RGBCurvesNode : public CurvesNode {
 public:
 	SHADER_NODE_CLASS(RGBCurvesNode)
+	void constant_fold(const ConstantFolder& folder);
 };
 
 class VectorCurvesNode : public CurvesNode {
 public:
 	SHADER_NODE_CLASS(VectorCurvesNode)
+	void constant_fold(const ConstantFolder& folder);
 };
 
 class RGBRampNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(RGBRampNode)
+	void constant_fold(const ConstantFolder& folder);
 	virtual int get_group() { return NODE_GROUP_LEVEL_1; }
 
 	array<float3> ramp;