diff options
Diffstat (limited to 'gfx/gl/DecomposeIntoNoRepeatTriangles.cpp')
| -rw-r--r-- | gfx/gl/DecomposeIntoNoRepeatTriangles.cpp | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/gfx/gl/DecomposeIntoNoRepeatTriangles.cpp b/gfx/gl/DecomposeIntoNoRepeatTriangles.cpp new file mode 100644 index 000000000..829c20187 --- /dev/null +++ b/gfx/gl/DecomposeIntoNoRepeatTriangles.cpp @@ -0,0 +1,173 @@ +/* -*- 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); +} + +static GLfloat +WrapTexCoord(GLfloat v) +{ + // This should return values in range [0, 1.0) + return v - floorf(v); +} + +void +DecomposeIntoNoRepeatTriangles(const gfx::IntRect& aTexCoordRect, + const gfx::IntSize& aTexSize, + RectTriangles& aRects, + bool aFlipY /* = false */) +{ + // normalize this + gfx::IntRect 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); + } +} + +} // namespace gl +} // namespace mozilla |