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-rw-r--r--gfx/gl/DecomposeIntoNoRepeatTriangles.cpp173
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
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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);
+}
+
+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