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
  14 namespace mozilla {
  15 namespace gl {
  16
  17 /** Helper for DecomposeIntoNoRepeatTriangles
  18   */
  19 class RectTriangles {
  20 public:
  21     typedef struct { GLfloat x,y; } coord;
  22
  23     // Always pass texture coordinates upright. If you want to flip the
  24     // texture coordinates emitted to the tex_coords array, set flip_y to
  25     // true.
  26     void addRect(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
  27                  GLfloat tx0, GLfloat ty0, GLfloat tx1, GLfloat ty1,
  28                  bool flip_y = false);
  29
  30     /**
  31       * these return a float pointer to the start of each array respectively.
  32       * Use it for glVertexAttribPointer calls.
  33       * We can return nullptr if we choose to use Vertex Buffer Objects here.
  34       */
  35     InfallibleTArray<coord>& vertCoords() {
  36         return mVertexCoords;
  37     }
  38
  39     InfallibleTArray<coord>& texCoords() {
  40         return mTexCoords;
  41     }
  42
  43     unsigned int elements() {
  44         return mVertexCoords.Length();
  45     }
  46 private:
  47     // Reserve inline storage for one quad (2 triangles, 3 coords).
  48     nsAutoTArray<coord, 6> mVertexCoords;
  49     nsAutoTArray<coord, 6> mTexCoords;
  50
  51     static void
  52     AppendRectToCoordArray(InfallibleTArray<coord>& array, GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1);
  53 };
  54
  55 /**
  56   * Decompose drawing the possibly-wrapped aTexCoordRect rectangle
  57   * of a texture of aTexSize into one or more rectangles (represented
  58   * as 2 triangles) and associated tex coordinates, such that
  59   * we don't have to use the REPEAT wrap mode. If aFlipY is true, the
  60   * texture coordinates will be specified vertically flipped.
  61   *
  62   * The resulting triangle vertex coordinates will be in the space of
  63   * (0.0, 0.0) to (1.0, 1.0) -- transform the coordinates appropriately
  64   * if you need a different space.
  65   *
  66   * The resulting vertex coordinates should be drawn using GL_TRIANGLES,
  67   * and rects.numRects * 3 * 6
  68   */
  69 void DecomposeIntoNoRepeatTriangles(const nsIntRect& aTexCoordRect,
  70                                     const nsIntSize& aTexSize,
  71                                     RectTriangles& aRects,
  72                                     bool aFlipY = false);
  73
  74 }
  75 }
  76
  77 #endif // DecomposeIntoNoRepeatTriangles_h_