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

3 files changed, 101 insertions, 33 deletions

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__ */
+