92 lines
3.1 KiB
C
92 lines
3.1 KiB
C
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/*
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* Copyright 2013 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef GrCoordTransform_DEFINED
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#define GrCoordTransform_DEFINED
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#include "GrEffect.h"
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#include "SkMatrix.h"
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#include "GrTexture.h"
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#include "GrTypes.h"
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/**
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* Coordinates available to GrEffect subclasses for requesting transformations. Transformed
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* coordinates are made available in the the portion of fragment shader emitted by the effect.
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*/
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enum GrCoordSet {
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/**
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* The user-space coordinates that map to the fragment being rendered. These coords account for
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* any change of coordinate system done on the CPU by GrContext before rendering, and also are
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* correct for draws that take explicit local coords rather than inferring them from the
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* primitive's positions (e.g. drawVertices). These are usually the coords a GrEffect wants.
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*/
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kLocal_GrCoordSet,
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/**
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* The actual vertex position. Note that GrContext may not draw using the original view matrix
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* specified by the caller, as it may have transformed vertices into another space. These are
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* usually not the coordinates a GrEffect wants.
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*/
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kPosition_GrCoordSet
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};
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/**
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* A class representing a linear transformation from one of the built-in coordinate sets (local or
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* position). GrEffects just define these transformations, and the framework does the rest of the
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* work to make the transformed coordinates available in their fragment shader.
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*/
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class GrCoordTransform : public SkNoncopyable {
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public:
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GrCoordTransform() {}
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/**
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* Create a transformation that maps [0, 1] to a texture's boundaries.
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*/
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GrCoordTransform(GrCoordSet sourceCoords, const GrTexture* texture) {
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this->reset(sourceCoords, texture);
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}
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/**
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* Create a transformation from a matrix. The optional texture parameter is used to infer if the
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* framework should internally do a y reversal to account for it being upside down by Skia's
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* coord convention.
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*/
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GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture = NULL) {
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this->reset(sourceCoords, m, texture);
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}
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void reset(GrCoordSet sourceCoords, const GrTexture* texture) {
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SkASSERT(NULL != texture);
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this->reset(sourceCoords, GrEffect::MakeDivByTextureWHMatrix(texture), texture);
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}
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void reset(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture = NULL) {
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fSourceCoords = sourceCoords;
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fMatrix = m;
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fReverseY = NULL != texture && kBottomLeft_GrSurfaceOrigin == texture->origin();
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}
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bool operator== (const GrCoordTransform& other) const {
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return fSourceCoords == other.fSourceCoords &&
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fMatrix.cheapEqualTo(other.fMatrix) &&
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fReverseY == other.fReverseY;
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}
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GrCoordSet sourceCoords() const { return fSourceCoords; }
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const SkMatrix& getMatrix() const { return fMatrix; }
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bool reverseY() const { return fReverseY; }
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private:
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GrCoordSet fSourceCoords;
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SkMatrix fMatrix;
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bool fReverseY;
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typedef SkNoncopyable INHERITED;
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};
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#endif
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