Do div-by-zero check for all gpus in ellipse/rr effects.

R=jvanverth@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/231093002

git-svn-id: http://skia.googlecode.com/svn/trunk@14110 2bbb7eff-a529-9590-31e7-b0007b416f81

3 files changed, 8 insertions, 16 deletions

diff --git a/src/gpu/GrOvalRenderer.cpp b/src/gpu/GrOvalRenderer.cpp
index 190bf9d257..2ade8cde07 100644
--- a/src/gpu/GrOvalRenderer.cpp
+++ b/src/gpu/GrOvalRenderer.cpp
@@ -230,11 +230,8 @@ public:
             builder->fsCodeAppend("\tfloat test = dot(scaledOffset, scaledOffset) - 1.0;\n");
             builder->fsCodeAppendf("\tvec2 grad = 2.0*scaledOffset*%s.xy;\n", fsRadiiName);
             builder->fsCodeAppend("\tfloat grad_dot = dot(grad, grad);\n");
-            // we need to clamp the length^2 of the gradiant vector to a non-zero value, because
-            // on the Nexus 4 the undefined result of inversesqrt(0) drops out an entire tile
-            if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-                builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-            }
+            // avoid calling inversesqrt on zero.
+            builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
             builder->fsCodeAppend("\tfloat invlen = inversesqrt(grad_dot);\n");
             builder->fsCodeAppend("\tfloat edgeAlpha = clamp(0.5-test*invlen, 0.0, 1.0);\n");
 
@@ -379,11 +376,8 @@ public:
                                    fsOffsetName0, fsOffsetName0, fsOffsetName0, fsOffsetName0);
 
             builder->fsCodeAppend("\tfloat grad_dot = dot(grad, grad);\n");
-            // we need to clamp the length^2 of the gradiant vector to a non-zero value, because
-            // on the Nexus 4 the undefined result of inversesqrt(0) drops out an entire tile
-            if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-                builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-            }
+            // avoid calling inversesqrt on zero.
+            builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
             builder->fsCodeAppend("\tfloat invlen = inversesqrt(grad_dot);\n");
             if (kHairline == ellipseEffect.getMode()) {
                 // can probably do this with one step
diff --git a/src/gpu/effects/GrOvalEffect.cpp b/src/gpu/effects/GrOvalEffect.cpp
index e033a896d8..97b977f754 100644
--- a/src/gpu/effects/GrOvalEffect.cpp
+++ b/src/gpu/effects/GrOvalEffect.cpp
@@ -317,9 +317,8 @@ void GLEllipseEffect::emitCode(GrGLShaderBuilder* builder,
     builder->fsCodeAppend("\t\tfloat implicit = dot(Z, d) - 1.0;\n");
     // grad_dot is the squared length of the gradient of the implicit.
     builder->fsCodeAppendf("\t\tfloat grad_dot = 4.0 * dot(Z, Z);\n");
-    if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-        builder->fsCodeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-    }
+    // avoid calling inversesqrt on zero.
+    builder->fsCodeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
     builder->fsCodeAppendf("\t\tfloat approx_dist = implicit * inversesqrt(grad_dot);\n");
 
     switch (ee.getEdgeType()) {
diff --git a/src/gpu/effects/GrRRectEffect.cpp b/src/gpu/effects/GrRRectEffect.cpp
index c013357064..bc79057478 100644
--- a/src/gpu/effects/GrRRectEffect.cpp
+++ b/src/gpu/effects/GrRRectEffect.cpp
@@ -572,9 +572,8 @@ void GLEllipticalRRectEffect::emitCode(GrGLShaderBuilder* builder,
     builder->fsCodeAppend("\t\tfloat implicit = dot(Z, dxy) - 1.0;\n");
     // grad_dot is the squared length of the gradient of the implicit.
     builder->fsCodeAppendf("\t\tfloat grad_dot = 4.0 * dot(Z, Z);\n");
-    if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-        builder->fsCodeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-    }
+    // avoid calling inversesqrt on zero.
+    builder->fsCodeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
     builder->fsCodeAppendf("\t\tfloat approx_dist = implicit * inversesqrt(grad_dot);\n");
 
     if (kFillAA_GrEffectEdgeType == erre.getEdgeType()) {