Add GrEllipseEdgeEffect

src/gpu/effects/GrEllipseEdgeEffect.cpp

+/*

[robertphillips, 2013/03/05 20:30:13]

2013

[jvanverth1, 2013/03/07 15:21:54]

Done.

+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrEllipseEdgeEffect.h"
+#include "gl/GrGLEffect.h"
+#include "gl/GrGLEffectMatrix.h"
+#include "gl/GrGLSL.h"
+#include "gl/GrGLTexture.h"
+#include "GrTBackendEffectFactory.h"
+#include "GrTexture.h"
+
+#define ELLIPSE_EDGE_ATTR0 "aEllipseEdge"
+
+class GrGLEllipseEdgeEffect : public GrGLEffect {
+public:
+    GrGLEllipseEdgeEffect(const GrBackendEffectFactory& factory, const GrEffectRef&)
+    : INHERITED (factory) {}
+
+    virtual void emitCode(GrGLShaderBuilder* builder,
+                          const GrEffectStage&,
+                          EffectKey key,
+                          const char* vertexCoords,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TextureSamplerArray& samplers) SK_OVERRIDE {
+        const char *vsName, *fsName;
+        builder->addVarying(kVec4f_GrSLType, "EllipseEdge", &vsName, &fsName);
+        builder->fVSAttrs.push_back().set(kVec4f_GrSLType,
+                                          GrGLShaderVar::kAttribute_TypeModifier,
+                                          ELLIPSE_EDGE_ATTR0);
+        builder->fVSCode.appendf("\t%s = " ELLIPSE_EDGE_ATTR0 ";\n", vsName);
+        

[robertphillips, 2013/03/05 20:30:13]

Reprise the layout of the vec4? e.g., w == xRad/yRad?

[jvanverth1, 2013/03/07 15:21:54]

Done.

+        builder->fFSCode.append("\tfloat edgeAlpha;\n");
+        builder->fFSCode.appendf("\tvec2 offset = (%s.xy - %s.xy);\n", builder->fragmentPosition(), fsName);
+        builder->fFSCode.appendf("\toffset.y *= %s.w;\n", fsName);
+        builder->fFSCode.append("\tfloat d = length(offset);\n");
+        builder->fFSCode.appendf("\tedgeAlpha = smoothstep(d - 0.5, d + 0.5, %s.z);\n", fsName);
+        builder->fFSCode.appendf("\t%s = ", outputColor);
+        GrGLSLModulate4f(&builder->fFSCode, inputColor, "edgeAlpha");
+        builder->fFSCode.append(";\n");
+
+    }
+
+    static inline EffectKey GenKey(const GrEffectStage& stage, const GrGLCaps&) {

[robertphillips, 2013/03/05 20:30:13]

// Why 0x1?

[jvanverth1, 2013/03/07 15:21:54]

Done.

+        return 0x1;
+    }
+
+    virtual void setData(const GrGLUniformManager& uman, const GrEffectStage& stage) SK_OVERRIDE {
+    }
+
+private:

[robertphillips, 2013/03/05 20:30:13]

unused?

[jvanverth1, 2013/03/07 15:21:54]

Done.

+    bool fDiscardIfOutsideEdge;
+    typedef GrGLEffect INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+GrEllipseEdgeEffect::GrEllipseEdgeEffect() : GrEffect() {
+    this->addVertexAttribName(ELLIPSE_EDGE_ATTR0);
+}
+
+void GrEllipseEdgeEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {

[robertphillips, 2013/03/05 20:30:13]

Remove dead code?

[jvanverth1, 2013/03/07 15:21:54]

Done.

+//    this->updateConstantColorComponentsForModulation(color, validFlags);
+    *validFlags = 0;
+}
+
+const GrBackendEffectFactory& GrEllipseEdgeEffect::getFactory() const {
+    return GrTBackendEffectFactory<GrEllipseEdgeEffect>::getInstance();
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+GR_DEFINE_EFFECT_TEST(GrEllipseEdgeEffect);
+
+GrEffectRef* GrEllipseEdgeEffect::TestCreate(SkMWCRandom* random,
+                                               GrContext* context,
+                                               GrTexture* textures[]) {
+    return GrEllipseEdgeEffect::Create();
+}