gecko-dev/gfx/gl/DecomposeIntoNoRepeatTriang...

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim: set ts=8 sts=4 et sw=4 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef DecomposeIntoNoRepeatTriangles_h_
#define DecomposeIntoNoRepeatTriangles_h_
#include "GLTypes.h"
#include "nsRect.h"
#include "nsTArray.h"
namespace mozilla {
namespace gl {
/** Helper for DecomposeIntoNoRepeatTriangles
*/
class RectTriangles {
public:
typedef struct { GLfloat x,y; } coord;
// Always pass texture coordinates upright. If you want to flip the
// texture coordinates emitted to the tex_coords array, set flip_y to
// true.
void addRect(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
GLfloat tx0, GLfloat ty0, GLfloat tx1, GLfloat ty1,
bool flip_y = false);
/**
* these return a float pointer to the start of each array respectively.
* Use it for glVertexAttribPointer calls.
* We can return nullptr if we choose to use Vertex Buffer Objects here.
*/
InfallibleTArray<coord>& vertCoords() {
return mVertexCoords;
}
InfallibleTArray<coord>& texCoords() {
return mTexCoords;
}
unsigned int elements() {
return mVertexCoords.Length();
}
private:
// Reserve inline storage for one quad (2 triangles, 3 coords).
nsAutoTArray<coord, 6> mVertexCoords;
nsAutoTArray<coord, 6> mTexCoords;
static void
AppendRectToCoordArray(InfallibleTArray<coord>& array, GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1);
};
/**
* Decompose drawing the possibly-wrapped aTexCoordRect rectangle
* of a texture of aTexSize into one or more rectangles (represented
* as 2 triangles) and associated tex coordinates, such that
* we don't have to use the REPEAT wrap mode. If aFlipY is true, the
* texture coordinates will be specified vertically flipped.
*
* The resulting triangle vertex coordinates will be in the space of
* (0.0, 0.0) to (1.0, 1.0) -- transform the coordinates appropriately
* if you need a different space.
*
* The resulting vertex coordinates should be drawn using GL_TRIANGLES,
* and rects.numRects * 3 * 6
*/
void DecomposeIntoNoRepeatTriangles(const gfx::IntRect& aTexCoordRect,
const gfx::IntSize& aTexSize,
RectTriangles& aRects,
bool aFlipY = false);
} // namespace gl
} // namespace mozilla
#endif // DecomposeIntoNoRepeatTriangles_h_