Add support for SGSR 1.0

SGSR stands for Snapdragon Game Super Resolution. It is an efficient
upscaler for mobile.

Split the upscaling passes into multiple methods in PostProcessManager.
Also, add a way to preserve the alpha channel in the FXAA pass.

android/filament-android/src/main/java/com/google/android/filament/View.java

@@ -1420,10 +1420,10 @@ public static class DynamicResolutionOptions {
         /**
          * Upscaling quality
          * LOW:    bilinear filtered blit. Fastest, poor quality
-         * MEDIUM: AMD FidelityFX FSR1 w/ mobile optimizations
+         * MEDIUM: Qualcomm Snapdragon Game Super Resolution (SGSR) 1.0
          * HIGH:   AMD FidelityFX FSR1 w/ mobile optimizations
          * ULTRA:  AMD FidelityFX FSR1
-         *      FSR1 require a well anti-aliased (MSAA or TAA), noise free scene.
+         *      FSR1 and SGSR require a well anti-aliased (MSAA or TAA), noise free scene. Avoid FXAA and dithering.
          *
          * The default upscaling quality is set to LOW.
          */

filament/CMakeLists.txt

@@ -252,6 +252,7 @@ set(MATERIAL_SRCS
         src/materials/fsr/fsr_easu_mobile.mat
         src/materials/fsr/fsr_easu_mobileF.mat
         src/materials/fsr/fsr_rcas.mat
+        src/materials/sgsr/sgsr1.mat
         src/materials/resolveDepth.mat
         src/materials/separableGaussianBlur.mat
         src/materials/skybox.mat
@@ -504,6 +505,12 @@ add_custom_command(
         APPEND
 )
 
+add_custom_command(
+        OUTPUT "${MATERIAL_DIR}/sgsr1.filamat"
+        DEPENDS src/materials/sgsr/sgsr1_shader_mobile.fs
+        APPEND
+)
+
 add_custom_command(
         OUTPUT "${MATERIAL_DIR}/separableGaussianBlur.filamat"
         DEPENDS src/materials/separableGaussianBlur.vs

filament/include/filament/Options.h

@@ -86,10 +86,10 @@ struct DynamicResolutionOptions {
     /**
      * Upscaling quality
      * LOW:    bilinear filtered blit. Fastest, poor quality
-     * MEDIUM: AMD FidelityFX FSR1 w/ mobile optimizations
+     * MEDIUM: Qualcomm Snapdragon Game Super Resolution (SGSR) 1.0
      * HIGH:   AMD FidelityFX FSR1 w/ mobile optimizations
      * ULTRA:  AMD FidelityFX FSR1
-     *      FSR1 require a well anti-aliased (MSAA or TAA), noise free scene.
+     *      FSR1 and SGSR require a well anti-aliased (MSAA or TAA), noise free scene. Avoid FXAA and dithering.
      *
      * The default upscaling quality is set to LOW.
      */

filament/src/PostProcessManager.h

@@ -89,7 +89,7 @@ class PostProcessManager {
         bool asSubpass{};
         bool customResolve{};
         bool translucent{};
-        bool fxaa{};
+        bool outputLuminance{}; // Whether to output luminance in the alpha channel. Ignored by the TRANSLUCENT variant.
         bool dithering{};
         backend::TextureFormat ldrFormat{};
     };
@@ -227,7 +227,7 @@ class PostProcessManager {
     // Anti-aliasing
     FrameGraphId<FrameGraphTexture> fxaa(FrameGraph& fg,
             FrameGraphId<FrameGraphTexture> input, Viewport const& vp,
-            backend::TextureFormat outFormat, bool translucent) noexcept;
+            backend::TextureFormat outFormat, bool preserveAlphaChannel) noexcept;
 
     // Temporal Anti-aliasing
     void TaaJitterCamera(
@@ -251,12 +251,25 @@ class PostProcessManager {
 
     // high quality upscaler
     //  - when translucent, reverts to LINEAR
-    //  - doens't handle sub-resouces
+    //  - doesn't handle sub-resouces
     FrameGraphId<FrameGraphTexture> upscale(FrameGraph& fg, bool translucent,
+            bool sourceHasLuminance, DynamicResolutionOptions dsrOptions,
+            FrameGraphId<FrameGraphTexture> input, Viewport const& vp,
+            FrameGraphTexture::Descriptor const& outDesc, backend::SamplerMagFilter filter) noexcept;
+
+    FrameGraphId<FrameGraphTexture> upscaleBilinear(FrameGraph& fg, bool translucent,
             DynamicResolutionOptions dsrOptions, FrameGraphId<FrameGraphTexture> input,
             Viewport const& vp, FrameGraphTexture::Descriptor const& outDesc,
             backend::SamplerMagFilter filter) noexcept;
 
+    FrameGraphId<FrameGraphTexture> upscaleFSR1(FrameGraph& fg,
+            DynamicResolutionOptions dsrOptions, FrameGraphId<FrameGraphTexture> input,
+            filament::Viewport const& vp, FrameGraphTexture::Descriptor const& outDesc) noexcept;
+
+    FrameGraphId<FrameGraphTexture> upscaleSGSR1(FrameGraph& fg, bool sourceHasLuminance,
+            DynamicResolutionOptions dsrOptions, FrameGraphId<FrameGraphTexture> input,
+            filament::Viewport const& vp, FrameGraphTexture::Descriptor const& outDesc) noexcept;
+
     FrameGraphId<FrameGraphTexture> rcas(
             FrameGraph& fg,
             float sharpness,

filament/src/details/Renderer.cpp

@@ -681,6 +681,9 @@ void FRenderer::renderJob(RootArenaScope& rootArenaScope, FView& view) {
              hasColorGrading &&
              !bloomOptions.enabled && !dofOptions.enabled && !taaOptions.enabled;
 
+    // whether we're scaled at all
+    bool scaled = any(notEqual(scale, float2(1.0f)));
+
     // asSubpass is disabled with TAA (although it's supported) because performance was degraded
     // on qualcomm hardware -- we might need a backend dependent toggle at some point
     const PostProcessManager::ColorGradingConfig colorGradingConfig{
@@ -695,18 +698,15 @@ void FRenderer::renderJob(RootArenaScope& rootArenaScope, FView& view) {
                     hasColorGrading &&
                     !engine.debug.renderer.disable_subpasses,
             .translucent = needsAlphaChannel,
-            .fxaa = hasFXAA,
+            .outputLuminance = hasFXAA || scaled, // ignored by translucent variants (false)
             .dithering = hasDithering,
-            .ldrFormat = (hasColorGrading && hasFXAA) ?
+            .ldrFormat = (hasColorGrading && (hasFXAA || scaled)) ?
                     TextureFormat::RGBA8 : getLdrFormat(needsAlphaChannel)
     };
 
     // by construction (msaaSampleCount) both asSubpass and customResolve can't be true
     assert_invariant(colorGradingConfig.asSubpass + colorGradingConfig.customResolve < 2);
 
-    // whether we're scaled at all
-     bool scaled = any(notEqual(scale, float2(1.0f)));
-
     // vp is the user defined viewport within the View
     filament::Viewport const& vp = view.getViewport();
 
@@ -1351,18 +1351,21 @@ void FRenderer::renderJob(RootArenaScope& rootArenaScope, FView& view) {
         }
 
         if (hasFXAA) {
-            input = ppm.fxaa(fg, input, xvp, colorGradingConfig.ldrFormat,
-                    !hasColorGrading || needsAlphaChannel);
+            bool const preserveAlphaChannel = needsAlphaChannel ||
+                    (hasColorGrading && colorGradingConfig.outputLuminance);
+            input = ppm.fxaa(fg, input, xvp, colorGradingConfig.ldrFormat, preserveAlphaChannel);
             // the padded buffer is resolved now
             xvp.left = xvp.bottom = 0;
             svp = xvp;
         }
         if (scaled) {
             mightNeedFinalBlit = false;
             auto viewport = DEBUG_DYNAMIC_SCALING ? xvp : vp;
-            input = ppm.upscale(fg, needsAlphaChannel, dsrOptions, input, xvp, {
-                    .width = viewport.width, .height = viewport.height,
-                    .format = colorGradingConfig.ldrFormat }, SamplerMagFilter::LINEAR);
+            bool const sourceHasLuminance = !needsAlphaChannel &&
+                    (hasColorGrading && colorGradingConfig.outputLuminance);
+            input = ppm.upscale(fg, needsAlphaChannel, sourceHasLuminance, dsrOptions, input, xvp, {
+                .width = viewport.width, .height = viewport.height,
+                .format = colorGradingConfig.ldrFormat }, SamplerMagFilter::LINEAR);
             xvp.left = xvp.bottom = 0;
             svp = xvp;
         }

filament/src/materials/colorGrading/colorGrading.mat

@@ -41,7 +41,7 @@ material {
         },
         {
             type : int,
-            name : fxaa
+            name : outputLuminance
         },
         {
             type : float,
@@ -166,10 +166,10 @@ void postProcess(inout PostProcessInputs postProcess) {
         color = dither(color, materialParams.temporalNoise);
     }
 
-    // kill alpha computations when opaque / fxaa luminance
+    // kill alpha computations when opaque / luminance
 #if POST_PROCESS_OPAQUE
     color.a = 1.0;
-    if (materialParams.fxaa > 0) {
+    if (materialParams.outputLuminance > 0) {
         color.a = luminance(color.rgb);
     }
 #endif

filament/src/materials/sgsr/LICENSE.txt

@@ -0,0 +1,29 @@
+Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+SPDX-License-Identifier: BSD-3-Clause

filament/src/materials/sgsr/sgsr1.mat

@@ -0,0 +1,80 @@
+material {
+    name : sgsr1,
+    parameters : [
+        {
+            type : sampler2d,
+            name : color,
+            precision: medium
+        },
+        {
+            type : float4,
+            name : viewport,
+            precision: high
+        }
+    ],
+    variables : [
+        vertex
+    ],
+    depthWrite : false,
+    depthCulling : false,
+    domain: postprocess
+}
+
+vertex {
+    void postProcessVertex(inout PostProcessVertexInputs postProcess) {
+        postProcess.normalizedUV = uvToRenderTargetUV(postProcess.normalizedUV);
+        postProcess.vertex.xy = postProcess.normalizedUV;
+    }
+}
+
+fragment {
+
+    void dummy(){}
+
+    precision mediump float;
+    precision highp int;
+
+#if defined(FILAMENT_HAS_FEATURE_TEXTURE_GATHER)
+    #define gather textureGather
+#else
+    vec4 gather(const mediump sampler2D color, highp vec2 p, const int comp) {
+        highp ivec2 i = ivec2(p * materialParams.viewport.zw - 0.5);
+        vec4 d;
+        d[0] = texelFetchOffset(color, i, 0, ivec2(0, 1))[comp];
+        d[1] = texelFetchOffset(color, i, 0, ivec2(1, 1))[comp];
+        d[2] = texelFetchOffset(color, i, 0, ivec2(1, 0))[comp];
+        d[3] = texelFetchOffset(color, i, 0, ivec2(0, 0))[comp];
+        return d;
+    }
+#endif
+
+/*
+* Operation modes:
+* RGBA -> 1
+* RGBY -> 3
+* LERP -> 4
+*/
+
+// SGSR cannot support translucency;
+// So we hijack the POST_PROCESS variant to select whether a luminance channel is present
+#if POST_PROCESS_OPAQUE
+#   define OperationMode 1
+#else
+#   define OperationMode 3
+#endif
+
+/*
+* If set, will use edge direction to improve visual quality
+* Expect a minimal cost increase
+*/
+#define UseEdgeDirection
+#define EdgeThreshold 8.0 / 255.0
+#define EdgeSharpness 2.0
+
+#include "sgsr1_shader_mobile.fs"
+
+    void postProcess(inout PostProcessInputs postProcess) {
+        highp vec4 vp[1] = vec4[1]( materialParams.viewport );
+        postProcess.color = sgsr(materialParams_color, variable_vertex.xy, vp);
+    }
+}