added SkSL saturate() function

Bug: skia:8220
Change-Id: Ib2e58ac77345a2aa53302c6c1484d52533556f93
Reviewed-on: https://skia-review.googlesource.com/145371
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

Author: Ethan Nicholas

src/core/SkColorMatrixFilterRowMajor255.cpp

@@ -221,7 +221,7 @@ class ColorMatrixEffect : public GrFragmentProcessor {
                                      uniformHandler->getUniformCStr(fMatrixHandle),
                                      args.fInputColor,
                                      uniformHandler->getUniformCStr(fVectorHandle));
-            fragBuilder->codeAppendf("\t%s = clamp(%s, 0.0, 1.0);\n",
+            fragBuilder->codeAppendf("\t%s = saturate(%s);\n",
                                      args.fOutputColor, args.fOutputColor);
             fragBuilder->codeAppendf("\t%s.rgb *= %s.a;\n", args.fOutputColor, args.fOutputColor);
         }

src/effects/SkHighContrastFilter.cpp

@@ -343,7 +343,7 @@ void GLHighContrastFilterEffect::emitCode(EmitArgs& args) {
     fragBuilder->codeAppendf("}");
 
     // Clamp.
-    fragBuilder->codeAppendf("color = clamp(color, 0, 1);");
+    fragBuilder->codeAppendf("color = saturate(color);");
 
     if (hcfe.linearize()) {
         fragBuilder->codeAppend("color.rgb = sqrt(color.rgb);");

src/effects/imagefilters/SkDisplacementMapEffect.cpp

@@ -551,7 +551,7 @@ void GrGLDisplacementMapEffect::emitCode(EmitArgs& args) {
 
     // Unpremultiply the displacement
     fragBuilder->codeAppendf(
-        "\t\t%s.rgb = (%s.a < %s) ? half3(0.0) : clamp(%s.rgb / %s.a, 0.0, 1.0);",
+        "\t\t%s.rgb = (%s.a < %s) ? half3(0.0) : saturate(%s.rgb / %s.a);",
         dColor, dColor, nearZero, dColor, dColor);
     SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[1]);
     fragBuilder->codeAppendf("\t\tfloat2 %s = %s + %s*(%s.",

src/effects/imagefilters/SkLightingImageFilter.cpp

@@ -1945,7 +1945,7 @@ void GrGLDiffuseLightingEffect::emitLightFunc(GrGLSLUniformHandler* uniformHandl
     };
     SkString lightBody;
     lightBody.appendf("\thalf colorScale = %s * dot(normal, surfaceToLight);\n", kd);
-    lightBody.appendf("\treturn half4(lightColor * clamp(colorScale, 0.0, 1.0), 1.0);\n");
+    lightBody.appendf("\treturn half4(lightColor * saturate(colorScale), 1.0);\n");
     fragBuilder->emitFunction(kHalf4_GrSLType,
                               "light",
                               SK_ARRAY_COUNT(gLightArgs),
@@ -2043,7 +2043,7 @@ void GrGLSpecularLightingEffect::emitLightFunc(GrGLSLUniformHandler* uniformHand
     lightBody.appendf("\thalf3 halfDir = half3(normalize(surfaceToLight + half3(0, 0, 1)));\n");
     lightBody.appendf("\tfloat colorScale = %s * pow(dot(normal, halfDir), %s);\n",
                       ks, shininess);
-    lightBody.appendf("\thalf3 color = lightColor * clamp(colorScale, 0.0, 1.0);\n");
+    lightBody.appendf("\thalf3 color = lightColor * saturate(colorScale);\n");
     lightBody.appendf("\treturn half4(color, max(max(color.r, color.g), color.b));\n");
     fragBuilder->emitFunction(kHalf4_GrSLType,
                               "light",

src/gpu/effects/GrArithmeticFP.fp

@@ -16,7 +16,7 @@ uniform float4 k;
 
 void main() {
     half4 dst = process(child);
-    sk_OutColor = clamp(k.x * sk_InColor * dst + k.y * sk_InColor + k.z * dst + k.w, 0, 1);
+    sk_OutColor = saturate(k.x * sk_InColor * dst + k.y * sk_InColor + k.z * dst + k.w);
     if (enforcePMColor) {
         sk_OutColor.rgb = min(sk_OutColor.rgb, sk_OutColor.a);
     }

src/gpu/effects/GrBezierEffect.cpp

@@ -175,7 +175,7 @@ void GrGLConicEffect::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
                                      func.c_str(), v.fsIn(), v.fsIn(), v.fsIn(), v.fsIn());
             fragBuilder->codeAppendf("%s = %s / %s;",
                                      edgeAlpha.c_str(), func.c_str(), gFM.c_str());
-            fragBuilder->codeAppendf("%s = clamp(0.5 - %s, 0.0, 1.0);",
+            fragBuilder->codeAppendf("%s = saturate(0.5 - %s);",
                                      edgeAlpha.c_str(), edgeAlpha.c_str());
             // Add line below for smooth cubic ramp
             // fragBuilder->codeAppend("edgeAlpha = edgeAlpha*edgeAlpha*(3.0-2.0*edgeAlpha);");
@@ -380,7 +380,7 @@ void GrGLQuadEffect::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
             fragBuilder->codeAppendf("edgeAlpha = (%s.x * %s.x - %s.y);",
                                      v.fsIn(), v.fsIn(), v.fsIn());
             fragBuilder->codeAppend("edgeAlpha = edgeAlpha / sqrt(dot(gF, gF));");
-            fragBuilder->codeAppend("edgeAlpha = clamp(0.5 - edgeAlpha, 0.0, 1.0);");
+            fragBuilder->codeAppend("edgeAlpha = saturate(0.5 - edgeAlpha);");
             // Add line below for smooth cubic ramp
             // fragBuilder->codeAppend("edgeAlpha = edgeAlpha*edgeAlpha*(3.0-2.0*edgeAlpha);");
             break;
@@ -615,7 +615,7 @@ void GrGLCubicEffect::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
                                      v.fsIn(), v.fsIn(), v.fsIn(), v.fsIn(), v.fsIn());
             fragBuilder->codeAppendf("%s = %s * inversesqrt(dot(%s, %s));",
                                      edgeAlpha.c_str(), func.c_str(), gF.c_str(), gF.c_str());
-            fragBuilder->codeAppendf("%s = clamp(0.5 - %s, 0.0, 1.0);",
+            fragBuilder->codeAppendf("%s = saturate(0.5 - %s);",
                                      edgeAlpha.c_str(), edgeAlpha.c_str());
             // Add line below for smooth cubic ramp
             // fragBuilder->codeAppendf("%s = %s * %s * (3.0 - 2.0 * %s);",

src/gpu/effects/GrCircleEffect.fp

@@ -60,7 +60,7 @@ void main() {
     @if (edgeType == GrClipEdgeType::kFillAA ||
          edgeType == GrClipEdgeType::kInverseFillAA ||
          edgeType == GrClipEdgeType::kHairlineAA) {
-        d = clamp(d, 0.0, 1.0);
+        d = saturate(d);
     } else {
         d = d > 0.5 ? 1.0 : 0.0;
     }

src/gpu/effects/GrConvexPolyEffect.cpp

@@ -54,7 +54,7 @@ void GrGLConvexPolyEffect::emitCode(EmitArgs& args) {
                                                              "1));\n",
                                  edgeArrayName, i);
         if (GrProcessorEdgeTypeIsAA(cpe.getEdgeType())) {
-            fragBuilder->codeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
+            fragBuilder->codeAppend("\t\tedge = saturate(edge);\n");
         } else {
             fragBuilder->codeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
         }

src/gpu/effects/GrDistanceFieldGeoProc.cpp

@@ -152,7 +152,7 @@ class GrGLDistanceFieldA8TextGeoProc : public GrGLSLGeometryProcessor {
             // doing gamma-correct rendering (to an sRGB or F16 buffer), then we actually want
             // distance mapped linearly to coverage, so use a linear step:
             fragBuilder->codeAppend(
-                "half val = clamp((distance + afwidth) / (2.0 * afwidth), 0.0, 1.0);");
+                "half val = saturate((distance + afwidth) / (2.0 * afwidth));");
         } else {
             fragBuilder->codeAppend("half val = smoothstep(-afwidth, afwidth, distance);");
         }
@@ -447,7 +447,7 @@ class GrGLDistanceFieldPathGeoProc : public GrGLSLGeometryProcessor {
         // mapped linearly to coverage, so use a linear step:
         if (isGammaCorrect) {
             fragBuilder->codeAppend(
-                "half val = clamp((distance + afwidth) / (2.0 * afwidth), 0.0, 1.0);");
+                "half val = saturate((distance + afwidth) / (2.0 * afwidth));");
         } else {
             fragBuilder->codeAppend("half val = smoothstep(-afwidth, afwidth, distance);");
         }
@@ -766,7 +766,7 @@ class GrGLDistanceFieldLCDTextGeoProc : public GrGLSLGeometryProcessor {
         // mapped linearly to coverage, so use a linear step:
         if (isGammaCorrect) {
             fragBuilder->codeAppendf("%s = "
-                "half4(clamp((distance + half3(afwidth)) / half3(2.0 * afwidth), 0.0, 1.0), 1.0);",
+                "half4(saturate((distance + half3(afwidth)) / half3(2.0 * afwidth)), 1.0);",
                 args.fOutputCoverage);
         } else {
             fragBuilder->codeAppendf(

src/gpu/effects/GrEllipseEffect.fp

@@ -91,13 +91,13 @@ void main() {
             alpha = approx_dist > 0.0 ? 0.0 : 1.0;
             break;
         case GrClipEdgeType::kFillAA:
-            alpha = clamp(0.5 - approx_dist, 0.0, 1.0);
+            alpha = saturate(0.5 - approx_dist);
             break;
         case GrClipEdgeType::kInverseFillBW:
             alpha = approx_dist > 0.0 ? 1.0 : 0.0;
             break;
         case GrClipEdgeType::kInverseFillAA:
-            alpha = clamp(0.5 + approx_dist, 0.0, 1.0);
+            alpha = saturate(0.5 + approx_dist);
             break;
         default:
             // hairline not supported