gfx/gl/DecomposeIntoNoRepeatTriangles.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /* vim: set ts=8 sts=4 et sw=4 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef DecomposeIntoNoRepeatTriangles_h_
   8 #define DecomposeIntoNoRepeatTriangles_h_
   9
  10 #include "GLTypes.h"
  11 #include "nsRect.h"
  12 #include "nsTArray.h"
  13 #include "gfx3DMatrix.h"
  14
  15 namespace mozilla {
  16 namespace gl {
  17
  18 /** Helper for DecomposeIntoNoRepeatTriangles
  19   */
  20 class RectTriangles {
  21 public:
  22     typedef struct { GLfloat x,y; } coord;
  23
  24     // Always pass texture coordinates upright. If you want to flip the
  25     // texture coordinates emitted to the tex_coords array, set flip_y to
  26     // true.
  27     void addRect(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
  28                  GLfloat tx0, GLfloat ty0, GLfloat tx1, GLfloat ty1,
  29                  bool flip_y = false);
  30
  31     /**
  32       * these return a float pointer to the start of each array respectively.
  33       * Use it for glVertexAttribPointer calls.
  34       * We can return nullptr if we choose to use Vertex Buffer Objects here.
  35       */
  36     InfallibleTArray<coord>& vertCoords() {
  37         return mVertexCoords;
  38     }
  39
  40     InfallibleTArray<coord>& texCoords() {
  41         return mTexCoords;
  42     }
  43
  44     unsigned int elements() {
  45         return mVertexCoords.Length();
  46     }
  47 private:
  48     // Reserve inline storage for one quad (2 triangles, 3 coords).
  49     nsAutoTArray<coord, 6> mVertexCoords;
  50     nsAutoTArray<coord, 6> mTexCoords;
  51
  52     static void
  53     AppendRectToCoordArray(InfallibleTArray<coord>& array, GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1);
  54 };
  55
  56 /**
  57   * Decompose drawing the possibly-wrapped aTexCoordRect rectangle
  58   * of a texture of aTexSize into one or more rectangles (represented
  59   * as 2 triangles) and associated tex coordinates, such that
  60   * we don't have to use the REPEAT wrap mode. If aFlipY is true, the
  61   * texture coordinates will be specified vertically flipped.
  62   *
  63   * The resulting triangle vertex coordinates will be in the space of
  64   * (0.0, 0.0) to (1.0, 1.0) -- transform the coordinates appropriately
  65   * if you need a different space.
  66   *
  67   * The resulting vertex coordinates should be drawn using GL_TRIANGLES,
  68   * and rects.numRects * 3 * 6
  69   */
  70 void DecomposeIntoNoRepeatTriangles(const nsIntRect& aTexCoordRect,
  71                                     const nsIntSize& aTexSize,
  72                                     RectTriangles& aRects,
  73                                     bool aFlipY = false);
  74
  75 }
  76 }
  77
  78 #endif // DecomposeIntoNoRepeatTriangles_h_