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/* -*- 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/. */
#include "DecomposeIntoNoRepeatTriangles.h"
#include "gfxMatrix.h"
namespace mozilla {
namespace gl {
void RectTriangles::AppendRectToCoordArray(nsTArray<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.MoveByX(-aTexSize.width);
while (tcr.Y() >= aTexSize.height) tcr.MoveByY(-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
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