From 6c5b9be7450903762f676522c32d65f7545730df Mon Sep 17 00:00:00 2001 From: Chris Craik Date: Wed, 27 Feb 2013 14:03:19 -0800 Subject: Fix T-junctions in layers' generated meshes bug:4128442 Currently we fix T-junctions for hardware layers, and for Canvas.saveLayer if the transform isn't rectAsRect. Ideally, hardware layers should lazily re-generate T-junction free geometry if the transform becomes non-rectAsRect Depends on frameworks/native change: https://googleplex-android-review.googlesource.com/#/c/277668/ which adds Region::createTJunctionFreeRegion() Change-Id: Ice75b4a1a4459ff835059ea81d70f7d1563fd96d --- libs/hwui/LayerRenderer.cpp | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) (limited to 'libs/hwui/LayerRenderer.cpp') diff --git a/libs/hwui/LayerRenderer.cpp b/libs/hwui/LayerRenderer.cpp index bc660cd8c2a9..14c7c39b39e3 100644 --- a/libs/hwui/LayerRenderer.cpp +++ b/libs/hwui/LayerRenderer.cpp @@ -123,13 +123,9 @@ Region* LayerRenderer::getRegion() { return &mLayer->region; } -// TODO: This implementation is flawed and can generate T-junctions -// in the mesh, which will in turn produce cracks when the -// mesh is rotated/skewed. The easiest way to fix this would -// be, for each row, to add new vertices shared with the previous -// row when the two rows share an edge. -// In practice, T-junctions do not appear often so this has yet -// to be fixed. +// TODO: This implementation uses a very simple approach to fixing T-junctions which keeps the +// results as rectangles, and is thus not necessarily efficient in the geometry +// produced. Eventually, it may be better to develop triangle-based mechanism. void LayerRenderer::generateMesh() { if (mLayer->region.isRect() || mLayer->region.isEmpty()) { if (mLayer->mesh) { @@ -145,8 +141,14 @@ void LayerRenderer::generateMesh() { return; } + // avoid T-junctions as they cause artifacts in between the resultant + // geometry when complex transforms occur. + // TODO: generate the safeRegion only if necessary based on drawing transform (see + // OpenGLRenderer::composeLayerRegion()) + Region safeRegion = Region::createTJunctionFreeRegion(mLayer->region); + size_t count; - const android::Rect* rects = mLayer->region.getArray(&count); + const android::Rect* rects = safeRegion.getArray(&count); GLsizei elementCount = count * 6; -- cgit v1.2.3-59-g8ed1b