commit f19544f28ba4d30066cc9b02c810f979ca789656
author Vishnu Nair <vishnun@google.com> Mon Feb 03 11:23:26 2020 -0800
committer Vishnu Nair <vishnun@google.com> Mon Feb 03 20:38:55 2020 +0000
tree a29370068828486e4a4fc24eb15811e3ab90103b
parent 466691bed8140fba59e581600e71cdcb6c64e8bd

Update shadow render code to use lookup texture

Optimizes performance on low end devices by avoiding exp() in the
fragment shader and lowering the precision of the shadow attributes
used in the shaders.

Test: adb shell su root dumpsys SurfaceFlinger --timestats -dump -maxlayers 0 on wembley
Test: atest SurfaceFlinger_test librenderengine_test
Test: shadows still look like shadows
Change-Id: I0e6e35a2f4f2d31b3126438ebb8b34d92a7d98c0

libs/renderengine/gl/ProgramCache.cpp

diff --git a/libs/renderengine/gl/ProgramCache.cpp b/libs/renderengine/gl/ProgramCache.cpp
index ba0e4ad..3ae35ec 100644
--- a/libs/renderengine/gl/ProgramCache.cpp
+++ b/libs/renderengine/gl/ProgramCache.cpp
@@ -550,7 +550,7 @@
 
 String8 ProgramCache::generateVertexShader(const Key& needs) {
     Formatter vs;
-    if (needs.isTexturing()) {
+    if (needs.hasTextureCoords()) {
         vs << "attribute vec4 texCoords;"
            << "varying vec2 outTexCoords;";
     }
@@ -559,16 +559,16 @@
         vs << "varying lowp vec2 outCropCoords;";
     }
     if (needs.drawShadows()) {
-        vs << "attribute vec4 shadowColor;";
-        vs << "varying vec4 outShadowColor;";
-        vs << "attribute vec4 shadowParams;";
-        vs << "varying vec3 outShadowParams;";
+        vs << "attribute lowp vec4 shadowColor;";
+        vs << "varying lowp vec4 outShadowColor;";
+        vs << "attribute lowp vec4 shadowParams;";
+        vs << "varying lowp vec3 outShadowParams;";
     }
     vs << "attribute vec4 position;"
        << "uniform mat4 projection;"
        << "uniform mat4 texture;"
        << "void main(void) {" << indent << "gl_Position = projection * position;";
-    if (needs.isTexturing()) {
+    if (needs.hasTextureCoords()) {
         vs << "outTexCoords = (texture * texCoords).st;";
     }
     if (needs.hasRoundedCorners()) {
@@ -592,11 +592,13 @@
     fs << "precision mediump float;";
 
     if (needs.getTextureTarget() == Key::TEXTURE_EXT) {
-        fs << "uniform samplerExternalOES sampler;"
-           << "varying vec2 outTexCoords;";
+        fs << "uniform samplerExternalOES sampler;";
     } else if (needs.getTextureTarget() == Key::TEXTURE_2D) {
-        fs << "uniform sampler2D sampler;"
-           << "varying vec2 outTexCoords;";
+        fs << "uniform sampler2D sampler;";
+    }
+
+    if (needs.hasTextureCoords()) {
+        fs << "varying vec2 outTexCoords;";
     }
 
     if (needs.hasRoundedCorners()) {
@@ -625,19 +627,17 @@
 
     if (needs.drawShadows()) {
         fs << R"__SHADER__(
-            varying vec4 outShadowColor;
-            varying vec3 outShadowParams;
+            varying lowp vec4 outShadowColor;
+            varying lowp vec3 outShadowParams;
 
             /**
              * Returns the shadow color.
              */
             vec4 getShadowColor()
             {
-                // exponential falloff function provided by UX
-                float d = length(outShadowParams.xy);
-                float distance = outShadowParams.z * (1.0 - d);
-                float factor = 1.0 - clamp(distance, 0.0, 1.0);
-                factor = exp(-factor * factor * 4.0) - 0.018;
+                lowp float d = length(outShadowParams.xy);
+                vec2 uv = vec2(outShadowParams.z * (1.0 - d), 0.5);
+                lowp float factor = texture2D(sampler, uv).a;
                 return outShadowColor * factor;
             }
             )__SHADER__";