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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkPatchUtils_DEFINED
#define SkPatchUtils_DEFINED
#include "SkColorPriv.h"
#include "SkMatrix.h"
class SK_API SkPatchUtils {
public:
/**
* Structure that holds the vertex data related to the tessellation of a patch. It is passed
* as a parameter to the function getVertexData which sets the points, colors and texture
* coordinates of the vertices and the indices for them to be drawn as triangles.
*/
struct VertexData {
int fVertexCount, fIndexCount;
SkPoint* fPoints;
SkPoint* fTexCoords;
uint32_t* fColors;
uint16_t* fIndices;
VertexData()
: fVertexCount(0)
, fIndexCount(0)
, fPoints(nullptr)
, fTexCoords(nullptr)
, fColors(nullptr)
, fIndices(nullptr) { }
~VertexData() {
delete[] fPoints;
delete[] fTexCoords;
delete[] fColors;
delete[] fIndices;
}
};
// Enums for control points based on the order specified in the constructor (clockwise).
enum CubicCtrlPts {
kTopP0_CubicCtrlPts = 0,
kTopP1_CubicCtrlPts = 1,
kTopP2_CubicCtrlPts = 2,
kTopP3_CubicCtrlPts = 3,
kRightP0_CubicCtrlPts = 3,
kRightP1_CubicCtrlPts = 4,
kRightP2_CubicCtrlPts = 5,
kRightP3_CubicCtrlPts = 6,
kBottomP0_CubicCtrlPts = 9,
kBottomP1_CubicCtrlPts = 8,
kBottomP2_CubicCtrlPts = 7,
kBottomP3_CubicCtrlPts = 6,
kLeftP0_CubicCtrlPts = 0,
kLeftP1_CubicCtrlPts = 11,
kLeftP2_CubicCtrlPts = 10,
kLeftP3_CubicCtrlPts = 9,
};
// Enum for corner also clockwise.
enum Corner {
kTopLeft_Corner = 0,
kTopRight_Corner,
kBottomRight_Corner,
kBottomLeft_Corner
};
enum {
kNumCtrlPts = 12,
kNumCorners = 4,
kNumPtsCubic = 4
};
/**
* Method that calculates a level of detail (number of subdivisions) for a patch in both axis.
*/
static SkISize GetLevelOfDetail(const SkPoint cubics[12], const SkMatrix* matrix);
/**
* Get the points corresponding to the top cubic of cubics.
*/
static void getTopCubic(const SkPoint cubics[12], SkPoint points[4]);
/**
* Get the points corresponding to the bottom cubic of cubics.
*/
static void getBottomCubic(const SkPoint cubics[12], SkPoint points[4]);
/**
* Get the points corresponding to the left cubic of cubics.
*/
static void getLeftCubic(const SkPoint cubics[12], SkPoint points[4]);
/**
* Get the points corresponding to the right cubic of cubics.
*/
static void getRightCubic(const SkPoint cubics[12], SkPoint points[4]);
/**
* Function that evaluates the coons patch interpolation.
* data refers to the pointer of the PatchData struct in which the tessellation data is set.
* cubics refers to the points of the cubics.
* lod refers the level of detail for each axis.
* colors refers to the corner colors that will be bilerp across the patch (optional parameter)
* texCoords refers to the corner texture coordinates that will be bilerp across the patch
(optional parameter)
*/
static bool getVertexData(SkPatchUtils::VertexData* data, const SkPoint cubics[12],
const SkColor colors[4], const SkPoint texCoords[4],
int lodX, int lodY);
};
#endif
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