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Cycles: implement partial constant folding for exponentiation. 

This is also an important mathematical operation that can be folded
if it is known that one argument is a certain constant. For colors
the operation is provided as a Gamma node.

The SVM Gamma node needs a small fix to make it follow the 0 ^ 0 == 1
rule, same as the Power node, or the Gamma node itself in OSL mode.

Reviewers: #cycles

Differential Revision: https://developer.blender.org/D2263
This commit is contained in:
Alexander Gavrilov 2016-09-29 00:35:53 +03:00
parent 95fa303efd
commit 40eedd5df9
5 changed files with 139 additions and 0 deletions
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3
intern/cycles/kernel/svm/svm_math_util.h
View File

@ -164,6 +164,9 @@ ccl_device float3 svm_math_blackbody_color(float t) {
ccl_device_inline float3 svm_math_gamma_color(float3 color, float gamma)
{
if(gamma == 0.0f)
return make_float3(1.0f, 1.0f, 1.0f);
if(color.x > 0.0f)
color.x = powf(color.x, gamma);
if(color.y > 0.0f)

22
intern/cycles/render/constant_fold.cpp
View File

@ -89,6 +89,19 @@ void ConstantFolder::make_zero() const
}
}
void ConstantFolder::make_one() const
{
if(output->type() == SocketType::FLOAT) {
make_constant(1.0f);
}
else if(SocketType::is_float3(output->type())) {
make_constant(make_float3(1.0f, 1.0f, 1.0f));
}
else {
assert(0);
}
}
void ConstantFolder::bypass(ShaderOutput *new_output) const
{
assert(new_output);
@ -321,6 +334,15 @@ void ConstantFolder::fold_math(NodeMath type, bool clamp) const
make_zero();
}
break;
case NODE_MATH_POWER:
/* 1 ^ X == X ^ 0 == 1 */
if(is_one(value1_in) || is_zero(value2_in)) {
make_one();
}
/* X ^ 1 == X */
else if(is_one(value2_in)) {
try_bypass_or_make_constant(value1_in, clamp);
}
default:
break;
}

1
intern/cycles/render/constant_fold.h
View File

@ -43,6 +43,7 @@ public:
void make_constant_clamp(float value, bool clamp) const;
void make_constant_clamp(float3 value, bool clamp) const;
void make_zero() const;
void make_one() const;
/* Bypass node, relinking to another output socket. */
void bypass(ShaderOutput *output) const;

13
intern/cycles/render/nodes.cpp
View File

@ -3896,6 +3896,19 @@ void GammaNode::constant_fold(const ConstantFolder& folder)
if(folder.all_inputs_constant()) {
folder.make_constant(svm_math_gamma_color(color, gamma));
}
else {
ShaderInput *color_in = input("Color");
ShaderInput *gamma_in = input("Gamma");
/* 1 ^ X == X ^ 0 == 1 */
if(folder.is_one(color_in) || folder.is_zero(gamma_in)) {
folder.make_one();
}
/* X ^ 1 == X */
else if(folder.is_one(gamma_in)) {
folder.try_bypass_or_make_constant(color_in, false);
}
}
}
void GammaNode::compile(SVMCompiler& compiler)

100
intern/cycles/test/render_graph_finalize_test.cpp
View File

@ -930,6 +930,72 @@ TEST(render_graph, constant_fold_gamma)
graph.finalize(&scene);
}
/*
* Tests: Gamma with one constant 0 input.
*/
TEST(render_graph, constant_fold_gamma_part_0)
{
DEFINE_COMMON_VARIABLES(builder, log);
EXPECT_ANY_MESSAGE(log);
INVALID_INFO_MESSAGE(log, "Folding Gamma_Cx::");
CORRECT_INFO_MESSAGE(log, "Folding Gamma_xC::Color to constant (1, 1, 1).");
builder
.add_attribute("Attribute")
/* constant on the left */
.add_node(ShaderNodeBuilder<GammaNode>("Gamma_Cx")
.set("Color", make_float3(0.0f, 0.0f, 0.0f)))
.add_connection("Attribute::Fac", "Gamma_Cx::Gamma")
/* constant on the right */
.add_node(ShaderNodeBuilder<GammaNode>("Gamma_xC")
.set("Gamma", 0.0f))
.add_connection("Attribute::Color", "Gamma_xC::Color")
/* output sum */
.add_node(ShaderNodeBuilder<MixNode>("Out")
.set(&MixNode::type, NODE_MIX_ADD)
.set(&MixNode::use_clamp, true)
.set("Fac", 1.0f))
.add_connection("Gamma_Cx::Color", "Out::Color1")
.add_connection("Gamma_xC::Color", "Out::Color2")
.output_color("Out::Color");
graph.finalize(&scene);
}
/*
* Tests: Gamma with one constant 1 input.
*/
TEST(render_graph, constant_fold_gamma_part_1)
{
DEFINE_COMMON_VARIABLES(builder, log);
EXPECT_ANY_MESSAGE(log);
CORRECT_INFO_MESSAGE(log, "Folding Gamma_Cx::Color to constant (1, 1, 1).");
CORRECT_INFO_MESSAGE(log, "Folding Gamma_xC::Color to socket Attribute::Color.");
builder
.add_attribute("Attribute")
/* constant on the left */
.add_node(ShaderNodeBuilder<GammaNode>("Gamma_Cx")
.set("Color", make_float3(1.0f, 1.0f, 1.0f)))
.add_connection("Attribute::Fac", "Gamma_Cx::Gamma")
/* constant on the right */
.add_node(ShaderNodeBuilder<GammaNode>("Gamma_xC")
.set("Gamma", 1.0f))
.add_connection("Attribute::Color", "Gamma_xC::Color")
/* output sum */
.add_node(ShaderNodeBuilder<MixNode>("Out")
.set(&MixNode::type, NODE_MIX_ADD)
.set(&MixNode::use_clamp, true)
.set("Fac", 1.0f))
.add_connection("Gamma_Cx::Color", "Out::Color1")
.add_connection("Gamma_xC::Color", "Out::Color2")
.output_color("Out::Color");
graph.finalize(&scene);
}
/*
* Tests: BrightnessContrast with all constant inputs.
*/
@ -1142,6 +1208,40 @@ TEST(render_graph, constant_fold_part_math_div_0)
graph.finalize(&scene);
}
/*
* Tests: partial folding for Math Power with known 0.
*/
TEST(render_graph, constant_fold_part_math_pow_0)
{
DEFINE_COMMON_VARIABLES(builder, log);
EXPECT_ANY_MESSAGE(log);
/* X ^ 0 == 1 */
INVALID_INFO_MESSAGE(log, "Folding Math_Cx::");
CORRECT_INFO_MESSAGE(log, "Folding Math_xC::Value to constant (1).");
INVALID_INFO_MESSAGE(log, "Folding Out::");
build_math_partial_test_graph(builder, NODE_MATH_POWER, 0.0f);
graph.finalize(&scene);
}
/*
* Tests: partial folding for Math Power with known 1.
*/
TEST(render_graph, constant_fold_part_math_pow_1)
{
DEFINE_COMMON_VARIABLES(builder, log);
EXPECT_ANY_MESSAGE(log);
/* 1 ^ X == 1; X ^ 1 == X */
CORRECT_INFO_MESSAGE(log, "Folding Math_Cx::Value to constant (1)");
CORRECT_INFO_MESSAGE(log, "Folding Math_xC::Value to socket Attribute::Fac.");
INVALID_INFO_MESSAGE(log, "Folding Out::");
build_math_partial_test_graph(builder, NODE_MATH_POWER, 1.0f);
graph.finalize(&scene);
}
/*
* Tests: Vector Math with all constant inputs.
*/