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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/. */

 #include "DecomposeIntoNoRepeatTriangles.h"

 #include "gfxMatrix.h"

 namespace mozilla {

 namespace gl {

 void

 RectTriangles::AppendRectToCoordArray(InfallibleTArray<coord>& array,

                                       GLfloat x0, GLfloat y0,

                                       GLfloat x1, GLfloat y1)

 {

     coord* v = array.AppendElements(6);

     v[0].x = x0; v[0].y = y0;

     v[1].x = x1; v[1].y = y0;

     v[2].x = x0; v[2].y = y1;

     v[3].x = x0; v[3].y = y1;

     v[4].x = x1; v[4].y = y0;

     v[5].x = x1; v[5].y = y1;

 }

 void

 RectTriangles::addRect(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,

                        GLfloat tx0, GLfloat ty0, GLfloat tx1, GLfloat ty1,

                        bool flip_y /* = false */)

 {

     if (flip_y) {

         std::swap(ty0, ty1);

     }

     AppendRectToCoordArray(mVertexCoords, x0, y0, x1, y1);

     AppendRectToCoordArray(mTexCoords, tx0, ty0, tx1, ty1);

 }

 bool

 RectTriangles::isSimpleQuad(gfx3DMatrix& aOutTextureTransform) const

 {

     if (mVertexCoords.Length() == 6 &&

         mVertexCoords[0].x == 0.0f &&

         mVertexCoords[0].y == 0.0f &&

         mVertexCoords[5].x == 1.0f &&

         mVertexCoords[5].y == 1.0f)

     {

         GLfloat tx0 = mTexCoords[0].x;

         GLfloat ty0 = mTexCoords[0].y;

         GLfloat tx1 = mTexCoords[5].x;

         GLfloat ty1 = mTexCoords[5].y;

         aOutTextureTransform = gfx3DMatrix::From2D(gfxMatrix(tx1 - tx0, 0, 0, ty1 - ty0, tx0, ty0));

         return true;

     }

     return false;

 }

 static GLfloat

 WrapTexCoord(GLfloat v)

 {

     // fmodf gives negative results for negative numbers;

     // that is, fmodf(0.75, 1.0) == 0.75, but

     // fmodf(-0.75, 1.0) == -0.75.  For the negative case,

     // the result we need is 0.25, so we add 1.0f.

     if (v < 0.0f) {

         return 1.0f + fmodf(v, 1.0f);

     }

     return fmodf(v, 1.0f);

 }

 void

 DecomposeIntoNoRepeatTriangles(const nsIntRect& aTexCoordRect,

                                const nsIntSize& aTexSize,

                                RectTriangles& aRects,

                                bool aFlipY /* = false */)

 {

     // normalize this

     nsIntRect tcr(aTexCoordRect);

     while (tcr.x >= aTexSize.width)

         tcr.x -= aTexSize.width;

     while (tcr.y >= aTexSize.height)

         tcr.y -= aTexSize.height;

     // Compute top left and bottom right tex coordinates

     GLfloat tl[2] =

         { GLfloat(tcr.x) / GLfloat(aTexSize.width),

           GLfloat(tcr.y) / GLfloat(aTexSize.height) };

     GLfloat br[2] =

         { GLfloat(tcr.XMost()) / GLfloat(aTexSize.width),

           GLfloat(tcr.YMost()) / GLfloat(aTexSize.height) };

     // then check if we wrap in either the x or y axis; if we do,

     // then also use fmod to figure out the "true" non-wrapping

     // texture coordinates.

     bool xwrap = false, ywrap = false;

     if (tcr.x < 0 || tcr.x > aTexSize.width ||

         tcr.XMost() < 0 || tcr.XMost() > aTexSize.width)

     {

         xwrap = true;

         tl[0] = WrapTexCoord(tl[0]);

         br[0] = WrapTexCoord(br[0]);

     }

     if (tcr.y < 0 || tcr.y > aTexSize.height ||

         tcr.YMost() < 0 || tcr.YMost() > aTexSize.height)

     {

         ywrap = true;

         tl[1] = WrapTexCoord(tl[1]);

         br[1] = WrapTexCoord(br[1]);

     }

     NS_ASSERTION(tl[0] >= 0.0f && tl[0] <= 1.0f &&

                  tl[1] >= 0.0f && tl[1] <= 1.0f &&

                  br[0] >= 0.0f && br[0] <= 1.0f &&

                  br[1] >= 0.0f && br[1] <= 1.0f,

                  "Somehow generated invalid texture coordinates");

     // If xwrap is false, the texture will be sampled from tl[0]

     // .. br[0].  If xwrap is true, then it will be split into tl[0]

     // .. 1.0, and 0.0 .. br[0].  Same for the Y axis.  The

     // destination rectangle is also split appropriately, according

     // to the calculated xmid/ymid values.

     // There isn't a 1:1 mapping between tex coords and destination coords;

     // when computing midpoints, we have to take that into account.  We

     // need to map the texture coords, which are (in the wrap case):

     // |tl->1| and |0->br| to the |0->1| range of the vertex coords.  So

     // we have the length (1-tl)+(br) that needs to map into 0->1.

     // These are only valid if there is wrap involved, they won't be used

     // otherwise.

     GLfloat xlen = (1.0f - tl[0]) + br[0];

     GLfloat ylen = (1.0f - tl[1]) + br[1];

     NS_ASSERTION(!xwrap || xlen > 0.0f, "xlen isn't > 0, what's going on?");

     NS_ASSERTION(!ywrap || ylen > 0.0f, "ylen isn't > 0, what's going on?");

     NS_ASSERTION(aTexCoordRect.width <= aTexSize.width &&

                  aTexCoordRect.height <= aTexSize.height, "tex coord rect would cause tiling!");

     if (!xwrap && !ywrap) {

         aRects.addRect(0.0f, 0.0f,

                        1.0f, 1.0f,

                        tl[0], tl[1],

                        br[0], br[1],

                        aFlipY);

     } else if (!xwrap && ywrap) {

         GLfloat ymid = (1.0f - tl[1]) / ylen;

         aRects.addRect(0.0f, 0.0f,

                        1.0f, ymid,

                        tl[0], tl[1],

                        br[0], 1.0f,

                        aFlipY);

         aRects.addRect(0.0f, ymid,

                        1.0f, 1.0f,

                        tl[0], 0.0f,

                        br[0], br[1],

                        aFlipY);

     } else if (xwrap && !ywrap) {

         GLfloat xmid = (1.0f - tl[0]) / xlen;

         aRects.addRect(0.0f, 0.0f,

                        xmid, 1.0f,

                        tl[0], tl[1],

                        1.0f, br[1],

                        aFlipY);

         aRects.addRect(xmid, 0.0f,

                        1.0f, 1.0f,

                        0.0f, tl[1],

                        br[0], br[1],

                        aFlipY);

     } else {

         GLfloat xmid = (1.0f - tl[0]) / xlen;

         GLfloat ymid = (1.0f - tl[1]) / ylen;

         aRects.addRect(0.0f, 0.0f,

                        xmid, ymid,

                        tl[0], tl[1],

                        1.0f, 1.0f,

                        aFlipY);

         aRects.addRect(xmid, 0.0f,

                        1.0f, ymid,

                        0.0f, tl[1],

                        br[0], 1.0f,

                        aFlipY);

         aRects.addRect(0.0f, ymid,

                        xmid, 1.0f,

                        tl[0], 0.0f,

                        1.0f, br[1],

                        aFlipY);

         aRects.addRect(xmid, ymid,

                        1.0f, 1.0f,

                        0.0f, 0.0f,

                        br[0], br[1],

                        aFlipY);

     }

 }

 }

 }