1 files changed, 44 insertions, 0 deletions
diff --git a/src/gpu/ccpr/GrCCConicShader.h b/src/gpu/ccpr/GrCCConicShader.h
new file mode 100644
index 0000000000..16b70e7072
--- /dev/null
+++ b/src/gpu/ccpr/GrCCConicShader.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrCCConicShader_DEFINED
+#define GrCCConicShader_DEFINED
+
+#include "ccpr/GrCCCoverageProcessor.h"
+
+/**
+ * This class renders the coverage of closed conic curves using the techniques outlined in
+ * "Resolution Independent Curve Rendering using Programmable Graphics Hardware" by Charles Loop and
+ * Jim Blinn:
+ *
+ * https://www.microsoft.com/en-us/research/wp-content/uploads/2005/01/p1000-loop.pdf
+ *
+ * The provided curves must be monotonic with respect to the vector of their closing edge [P2 - P0].
+ * (Use GrCCGeometry::conicTo().)
+ */
+class GrCCConicShader : public GrCCCoverageProcessor::Shader {
+public:
+    void emitSetupCode(GrGLSLVertexGeoBuilder*, const char* pts, const char* wind,
+                       const char** outHull4) const override;
+
+    void onEmitVaryings(GrGLSLVaryingHandler*, GrGLSLVarying::Scope, SkString* code,
+                        const char* position, const char* coverage,
+                        const char* cornerCoverage) override;
+
+    void onEmitFragmentCode(GrGLSLFPFragmentBuilder*, const char* outputCoverage) const override;
+
+private:
+    void calcHullCoverage(SkString* code, const char* klm, const char* grad,
+                          const char* outputCoverage) const;
+
+    const GrShaderVar fKLMMatrix{"klm_matrix", kFloat3x3_GrSLType};
+    const GrShaderVar fControlPoint{"control_point", kFloat2_GrSLType};
+    GrGLSLVarying fKLM_fWind;
+    GrGLSLVarying fGrad_fCorner;
+};
+
+#endif