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-rw-r--r--libs/shaders/shaders.cpp361
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diff --git a/libs/shaders/shaders.cpp b/libs/shaders/shaders.cpp
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+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <shaders/shaders.h>
+
+#include <tonemap/tonemap.h>
+
+#include <optional>
+
+#include <math/mat4.h>
+#include <system/graphics-base-v1.0.h>
+#include <ui/ColorSpace.h>
+
+namespace android::shaders {
+
+static aidl::android::hardware::graphics::common::Dataspace toAidlDataspace(
+ ui::Dataspace dataspace) {
+ return static_cast<aidl::android::hardware::graphics::common::Dataspace>(dataspace);
+}
+
+static void generateEOTF(ui::Dataspace dataspace, std::string& shader) {
+ switch (dataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ shader.append(R"(
+
+ float3 EOTF(float3 color) {
+ float m1 = (2610.0 / 4096.0) / 4.0;
+ float m2 = (2523.0 / 4096.0) * 128.0;
+ float c1 = (3424.0 / 4096.0);
+ float c2 = (2413.0 / 4096.0) * 32.0;
+ float c3 = (2392.0 / 4096.0) * 32.0;
+
+ float3 tmp = pow(clamp(color, 0.0, 1.0), 1.0 / float3(m2));
+ tmp = max(tmp - c1, 0.0) / (c2 - c3 * tmp);
+ return pow(tmp, 1.0 / float3(m1));
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_HLG:
+ shader.append(R"(
+ float EOTF_channel(float channel) {
+ const float a = 0.17883277;
+ const float b = 0.28466892;
+ const float c = 0.55991073;
+ return channel <= 0.5 ? channel * channel / 3.0 :
+ (exp((channel - c) / a) + b) / 12.0;
+ }
+
+ float3 EOTF(float3 color) {
+ return float3(EOTF_channel(color.r), EOTF_channel(color.g),
+ EOTF_channel(color.b));
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_LINEAR:
+ shader.append(R"(
+ float3 EOTF(float3 color) {
+ return color;
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_SRGB:
+ default:
+ shader.append(R"(
+
+ float EOTF_sRGB(float srgb) {
+ return srgb <= 0.04045 ? srgb / 12.92 : pow((srgb + 0.055) / 1.055, 2.4);
+ }
+
+ float3 EOTF_sRGB(float3 srgb) {
+ return float3(EOTF_sRGB(srgb.r), EOTF_sRGB(srgb.g), EOTF_sRGB(srgb.b));
+ }
+
+ float3 EOTF(float3 srgb) {
+ return sign(srgb.rgb) * EOTF_sRGB(abs(srgb.rgb));
+ }
+ )");
+ break;
+ }
+}
+
+static void generateXYZTransforms(std::string& shader) {
+ shader.append(R"(
+ uniform float4x4 in_rgbToXyz;
+ uniform float4x4 in_xyzToRgb;
+ float3 ToXYZ(float3 rgb) {
+ return (in_rgbToXyz * float4(rgb, 1.0)).rgb;
+ }
+
+ float3 ToRGB(float3 xyz) {
+ return clamp((in_xyzToRgb * float4(xyz, 1.0)).rgb, 0.0, 1.0);
+ }
+ )");
+}
+
+// Conversion from relative light to absolute light (maps from [0, 1] to [0, maxNits])
+static void generateLuminanceScalesForOOTF(ui::Dataspace inputDataspace,
+ ui::Dataspace outputDataspace, std::string& shader) {
+ switch (inputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * 10000.0;
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_HLG:
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * 1000.0 * pow(xyz.y, 0.2);
+ }
+ )");
+ break;
+ default:
+ switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ case HAL_DATASPACE_TRANSFER_HLG:
+ // SDR -> HDR tonemap
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * in_libtonemap_inputMaxLuminance;
+ }
+ )");
+ break;
+ default:
+ // Input and output are both SDR, so no tone-mapping is expected so
+ // no-op the luminance normalization.
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * in_libtonemap_displayMaxLuminance;
+ }
+ )");
+ break;
+ }
+ }
+}
+
+// Normalizes from absolute light back to relative light (maps from [0, maxNits] back to [0, 1])
+static void generateLuminanceNormalizationForOOTF(ui::Dataspace outputDataspace,
+ std::string& shader) {
+ switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / 10000.0;
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_HLG:
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / 1000.0 * pow(xyz.y / 1000.0, -0.2 / 1.2);
+ }
+ )");
+ break;
+ default:
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / in_libtonemap_displayMaxLuminance;
+ }
+ )");
+ break;
+ }
+}
+
+static void generateOOTF(ui::Dataspace inputDataspace, ui::Dataspace outputDataspace,
+ std::string& shader) {
+ shader.append(tonemap::getToneMapper()
+ ->generateTonemapGainShaderSkSL(toAidlDataspace(inputDataspace),
+ toAidlDataspace(outputDataspace))
+ .c_str());
+
+ generateLuminanceScalesForOOTF(inputDataspace, outputDataspace, shader);
+ generateLuminanceNormalizationForOOTF(outputDataspace, shader);
+
+ shader.append(R"(
+ float3 OOTF(float3 linearRGB, float3 xyz) {
+ float3 scaledLinearRGB = ScaleLuminance(linearRGB);
+ float3 scaledXYZ = ScaleLuminance(xyz);
+
+ float gain = libtonemap_LookupTonemapGain(scaledLinearRGB, scaledXYZ);
+
+ return NormalizeLuminance(scaledXYZ * gain);
+ }
+ )");
+}
+
+static void generateOETF(ui::Dataspace dataspace, std::string& shader) {
+ switch (dataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ shader.append(R"(
+
+ float3 OETF(float3 xyz) {
+ float m1 = (2610.0 / 4096.0) / 4.0;
+ float m2 = (2523.0 / 4096.0) * 128.0;
+ float c1 = (3424.0 / 4096.0);
+ float c2 = (2413.0 / 4096.0) * 32.0;
+ float c3 = (2392.0 / 4096.0) * 32.0;
+
+ float3 tmp = pow(xyz, float3(m1));
+ tmp = (c1 + c2 * tmp) / (1.0 + c3 * tmp);
+ return pow(tmp, float3(m2));
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_HLG:
+ shader.append(R"(
+ float OETF_channel(float channel) {
+ const float a = 0.17883277;
+ const float b = 0.28466892;
+ const float c = 0.55991073;
+ return channel <= 1.0 / 12.0 ? sqrt(3.0 * channel) :
+ a * log(12.0 * channel - b) + c;
+ }
+
+ float3 OETF(float3 linear) {
+ return float3(OETF_channel(linear.r), OETF_channel(linear.g),
+ OETF_channel(linear.b));
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_LINEAR:
+ shader.append(R"(
+ float3 OETF(float3 linear) {
+ return linear;
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_SRGB:
+ default:
+ shader.append(R"(
+ float OETF_sRGB(float linear) {
+ return linear <= 0.0031308 ?
+ linear * 12.92 : (pow(linear, 1.0 / 2.4) * 1.055) - 0.055;
+ }
+
+ float3 OETF_sRGB(float3 linear) {
+ return float3(OETF_sRGB(linear.r), OETF_sRGB(linear.g), OETF_sRGB(linear.b));
+ }
+
+ float3 OETF(float3 linear) {
+ return sign(linear.rgb) * OETF_sRGB(abs(linear.rgb));
+ }
+ )");
+ break;
+ }
+}
+
+static void generateEffectiveOOTF(bool undoPremultipliedAlpha, std::string& shader) {
+ shader.append(R"(
+ uniform shader child;
+ half4 main(float2 xy) {
+ float4 c = float4(child.eval(xy));
+ )");
+ if (undoPremultipliedAlpha) {
+ shader.append(R"(
+ c.rgb = c.rgb / (c.a + 0.0019);
+ )");
+ }
+ shader.append(R"(
+ float3 linearRGB = EOTF(c.rgb);
+ float3 xyz = ToXYZ(linearRGB);
+ c.rgb = OETF(ToRGB(OOTF(linearRGB, xyz)));
+ )");
+ if (undoPremultipliedAlpha) {
+ shader.append(R"(
+ c.rgb = c.rgb * (c.a + 0.0019);
+ )");
+ }
+ shader.append(R"(
+ return c;
+ }
+ )");
+}
+static ColorSpace toColorSpace(ui::Dataspace dataspace) {
+ switch (dataspace & HAL_DATASPACE_STANDARD_MASK) {
+ case HAL_DATASPACE_STANDARD_BT709:
+ return ColorSpace::sRGB();
+ break;
+ case HAL_DATASPACE_STANDARD_DCI_P3:
+ return ColorSpace::DisplayP3();
+ break;
+ case HAL_DATASPACE_STANDARD_BT2020:
+ return ColorSpace::BT2020();
+ break;
+ default:
+ return ColorSpace::sRGB();
+ break;
+ }
+}
+
+std::string buildLinearEffectSkSL(const LinearEffect& linearEffect) {
+ std::string shaderString;
+ generateEOTF(linearEffect.fakeInputDataspace == ui::Dataspace::UNKNOWN
+ ? linearEffect.inputDataspace
+ : linearEffect.fakeInputDataspace,
+ shaderString);
+ generateXYZTransforms(shaderString);
+ generateOOTF(linearEffect.inputDataspace, linearEffect.outputDataspace, shaderString);
+ generateOETF(linearEffect.outputDataspace, shaderString);
+ generateEffectiveOOTF(linearEffect.undoPremultipliedAlpha, shaderString);
+ return shaderString;
+}
+
+template <typename T, std::enable_if_t<std::is_trivially_copyable<T>::value, bool> = true>
+std::vector<uint8_t> buildUniformValue(T value) {
+ std::vector<uint8_t> result;
+ result.resize(sizeof(value));
+ std::memcpy(result.data(), &value, sizeof(value));
+ return result;
+}
+
+// Generates a list of uniforms to set on the LinearEffect shader above.
+std::vector<tonemap::ShaderUniform> buildLinearEffectUniforms(const LinearEffect& linearEffect,
+ const mat4& colorTransform,
+ float maxDisplayLuminance,
+ float maxLuminance) {
+ std::vector<tonemap::ShaderUniform> uniforms;
+ if (linearEffect.inputDataspace == linearEffect.outputDataspace) {
+ uniforms.push_back({.name = "in_rgbToXyz", .value = buildUniformValue<mat4>(mat4())});
+ uniforms.push_back(
+ {.name = "in_xyzToRgb", .value = buildUniformValue<mat4>(colorTransform)});
+ } else {
+ ColorSpace inputColorSpace = toColorSpace(linearEffect.inputDataspace);
+ ColorSpace outputColorSpace = toColorSpace(linearEffect.outputDataspace);
+ uniforms.push_back({.name = "in_rgbToXyz",
+ .value = buildUniformValue<mat4>(mat4(inputColorSpace.getRGBtoXYZ()))});
+ uniforms.push_back({.name = "in_xyzToRgb",
+ .value = buildUniformValue<mat4>(
+ colorTransform * mat4(outputColorSpace.getXYZtoRGB()))});
+ }
+
+ tonemap::Metadata metadata{.displayMaxLuminance = maxDisplayLuminance,
+ // If the input luminance is unknown, use display luminance (aka,
+ // no-op any luminance changes)
+ // This will be the case for eg screenshots in addition to
+ // uncalibrated displays
+ .contentMaxLuminance =
+ maxLuminance > 0 ? maxLuminance : maxDisplayLuminance};
+
+ for (const auto uniform : tonemap::getToneMapper()->generateShaderSkSLUniforms(metadata)) {
+ uniforms.push_back(uniform);
+ }
+
+ return uniforms;
+}
+
+} // namespace android::shaders \ No newline at end of file
generated by cgit v1.2.3-59-g8ed1b (git 2.39.0) at 2025-10-21 02:04:11 +0000