/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 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.
   */
  nsTArray<coord>& vertCoords() { return mVertexCoords; }

  nsTArray<coord>& texCoords() { return mTexCoords; }

  unsigned int elements() { return mVertexCoords.Length(); }

 private:
  // Reserve inline storage for one quad (2 triangles, 3 coords).
  AutoTArray<coord, 6> mVertexCoords;
  AutoTArray<coord, 6> mTexCoords;

  static void AppendRectToCoordArray(nsTArray<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_