Use threshold of 1 texture coord value per pixel w/ nearest neighbor.

include/gpu/GrCoordTransform.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrCoordTransform_DEFINED
 #define GrCoordTransform_DEFINED
 
@@ skipping 30 matching lines @@
  * A class representing a linear transformation from one of the built-in coordinate sets (local or
  * position). GrProcessors just define these transformations, and the framework does the rest of the
  * work to make the transformed coordinates available in their fragment shader.
  */
 class GrCoordTransform : SkNoncopyable {
 public:
     GrCoordTransform() { SkDEBUGCODE(fInProcessor = false); }
 
     /**
      * Create a transformation that maps [0, 1] to a texture's boundaries. The precision is inferred
-     * from the texture size.
+     * from the texture size and filter. The texture origin also implies whether a y-reversal should
+     * be performed.
      */
-    GrCoordTransform(GrCoordSet sourceCoords, const GrTexture* texture) {
+    GrCoordTransform(GrCoordSet sourceCoords,
+                     const GrTexture* texture,
+                     GrTextureParams::FilterMode filter) {
         SkASSERT(texture);
         SkDEBUGCODE(fInProcessor = false);
-        this->reset(sourceCoords, texture);
+        this->reset(sourceCoords, texture, filter);
     }
 
     /**
-     * Create a transformation from a matrix. The texture parameter is used to infer if the
-     * framework should internally do a y reversal to account for it being upside down by Skia's
-     * coord convention and the precision of the shader variables used to implement the coord
-     * transform.
+     * Create a transformation from a matrix. The precision is inferred from the texture size and
+     * filter. The texture origin also implies whether a y-reversal should be performed.
      */
-    GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture) {
+    GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m,
+                     const GrTexture* texture, GrTextureParams::FilterMode filter) {
         SkDEBUGCODE(fInProcessor = false);
         SkASSERT(texture);
-        this->reset(sourceCoords, m, texture);
+        this->reset(sourceCoords, m, texture, filter);
     }
 
     /**
      * Create a transformation that applies the matrix to a coord set.
      */
     GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m,
                      GrSLPrecision precision = kDefault_GrSLPrecision) {
         SkDEBUGCODE(fInProcessor = false);
         this->reset(sourceCoords, m, precision);
     }
 
-    void reset(GrCoordSet sourceCoords, const GrTexture* texture) {
+    void reset(GrCoordSet sourceCoords, const GrTexture* texture,
+               GrTextureParams::FilterMode filter) {
         SkASSERT(!fInProcessor);
         SkASSERT(texture);
-        this->reset(sourceCoords, MakeDivByTextureWHMatrix(texture), texture);
+        this->reset(sourceCoords, MakeDivByTextureWHMatrix(texture), texture, filter);
     }
 
-    void reset(GrCoordSet, const SkMatrix&, const GrTexture*);
+    void reset(GrCoordSet, const SkMatrix&, const GrTexture*, GrTextureParams::FilterMode filter);
     void reset(GrCoordSet sourceCoords, const SkMatrix& m,
                GrSLPrecision precision = kDefault_GrSLPrecision);
 
     GrCoordTransform& operator= (const GrCoordTransform& that) {
         SkASSERT(!fInProcessor);
         fSourceCoords = that.fSourceCoords;
         fMatrix = that.fMatrix;
         fReverseY = that.fReverseY;
         fPrecision = that.fPrecision;
         return *this;
@@ skipping 40 matching lines @@
 
 #ifdef SK_DEBUG
 public:
     void setInProcessor() const { fInProcessor = true; }
 private:
     mutable bool fInProcessor;
 #endif
 };
 
 #endif