[webkit-changes] [93387] trunk

Thu, 18 Aug 2011 22:44:59 -0700

Title: [93387] trunk
Revision
93387
Author
commit-qu...@webkit.org
Date
2011-08-18 22:44:52 -0700 (Thu, 18 Aug 2011)

Log Message

Computing screen-space transform for LayerChromium and CCLayerImpl
https://bugs.webkit.org/show_bug.cgi?id=66114

Source/WebCore:

Added a data member to LayerChromium and CCLayerImpl that holds
the screen-space transform.   The transform is computed in
calculateDrawTransformsAndVisibility(), which is used during
updating (LayerChromium) and drawing (CCLayerImpl).

Also fixed a FIXME in LayerRendererChromium::drawLayer, which
was not computing the entire hierarchy of transforms to determine
back-face visibility.  Now it simply uses the world space transform.

Patch by Shawn Singh <shawnsi...@chromium.org> on 2011-08-18
Reviewed by James Robinson.

Test: compositing/backface-visibility-hierarchical-transform.html

* platform/graphics/chromium/LayerChromium.h:
(WebCore::LayerChromium::screenSpaceTransform):
(WebCore::LayerChromium::setScreenSpaceTransform):
* platform/graphics/chromium/LayerRendererChromium.cpp:
(WebCore::LayerRendererChromium::updateLayers):
(WebCore::LayerRendererChromium::drawLayersInternal):
(WebCore::LayerRendererChromium::drawLayer):
* platform/graphics/chromium/cc/CCLayerImpl.h:
(WebCore::CCLayerImpl::screenSpaceTransform):
(WebCore::CCLayerImpl::setScreenSpaceTransform):

LayoutTests:

This case tests if backface visibility properly accounts for a hierarchy
of transforms.  In particular, this test forces Chromium to create a
hierarchy of RenderSurfaces.

Patch by Shawn Singh <shawnsi...@chromium.org> on 2011-08-18
Reviewed by James Robinson.

* compositing/backface-visibility-hierarchical-transform-expected.png: Added.
* compositing/backface-visibility-hierarchical-transform-expected.txt: Added.
* compositing/backface-visibility-hierarchical-transform.html: Added.

Modified Paths

Added Paths

Diff

Modified: trunk/LayoutTests/ChangeLog (93386 => 93387)


--- trunk/LayoutTests/ChangeLog	2011-08-19 04:51:38 UTC (rev 93386)
+++ trunk/LayoutTests/ChangeLog	2011-08-19 05:44:52 UTC (rev 93387)
@@ -1,3 +1,18 @@
+2011-08-18  Shawn Singh  <shawnsi...@chromium.org>
+
+        Computing screen-space transform for LayerChromium and CCLayerImpl
+        https://bugs.webkit.org/show_bug.cgi?id=66114
+
+        This case tests if backface visibility properly accounts for a hierarchy
+        of transforms.  In particular, this test forces Chromium to create a
+        hierarchy of RenderSurfaces.
+
+        Reviewed by James Robinson.
+
+        * compositing/backface-visibility-hierarchical-transform-expected.png: Added.
+        * compositing/backface-visibility-hierarchical-transform-expected.txt: Added.
+        * compositing/backface-visibility-hierarchical-transform.html: Added.
+
 2011-08-18  Ben Wells  <benwe...@chromium.org>
 
         [skia] -webkit-transform breaks -webkit-mask

Added: trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform-expected.png (0 => 93387)


--- trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform-expected.png	                        (rev 0)
+++ trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform-expected.png	2011-08-19 05:44:52 UTC (rev 93387)
@@ -0,0 +1,6 @@
+\x89PNG
+
+
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Added: trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform-expected.txt (0 => 93387)


--- trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform-expected.txt	                        (rev 0)
+++ trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform-expected.txt	2011-08-19 05:44:52 UTC (rev 93387)
@@ -0,0 +1 @@
+This test is only useful as a pixel test

Added: trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform.html (0 => 93387)


--- trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform.html	                        (rev 0)
+++ trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform.html	2011-08-19 05:44:52 UTC (rev 93387)
@@ -0,0 +1,95 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <style type="text/css" media="screen">
+    div {
+      height: 100px;
+      width: 100px;
+    }
+
+    .red {
+        background-color: red;
+    }
+
+    .green {
+        background-color: green;
+    }
+
+    .test1location {
+        position: absolute;
+        top: 10px;
+        left: 10px;
+    }
+
+    .test2location {
+        position: absolute;
+        top: 120px;
+        left: 10px;
+    }
+
+    .preserves3d {
+      -webkit-transform-style: preserve-3d;
+    }
+
+    .firstRenderSurface {
+      -webkit-transform: rotateY(180deg);
+      -webkit-transform-style: flat;
+    }
+
+    .secondRenderSurface {
+      -webkit-transform: rotateY(0deg);
+      -webkit-transform-style: flat;
+    }
+
+    .backfaceVisible {
+      -webkit-backface-visibility: visible;
+    }
+
+    .backfaceHidden {
+      -webkit-backface-visibility: hidden;
+    }
+  </style>
+</head>
+<body>
+
+  <!-- In the pixel results, two green squares should be visible. -->
+  <!-- This tests whether backface culling is accounting for the hierarchy of transforms -->
+
+  <div class="test1location red">
+  </div>
+  <div class="test1location">
+    <div class="preserves3d">
+      <div class="firstRenderSurface">
+        <div class="preserves3d">
+          <div class="secondRenderSurface">
+            <div class="preserves3d backfaceVisible green">
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+
+  <div class="test2location green">
+  </div>
+  <div class="test2location">
+    <div class="preserves3d">
+      <div class="firstRenderSurface">
+        <div class="preserves3d">
+          <div class="secondRenderSurface">
+            <div class="preserves3d backfaceHidden red">
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+
+  <script>
+  if (window.layoutTestController) {
+    layoutTestController.dumpAsText(true);  // This is only useful as a pixel test.
+    document.write("<span style='position:absolute; top:-5000px'>This test is only useful as a pixel test</span>");
+  }
+  </script>
+</body>
+</html>
Property changes on: trunk/LayoutTests/compositing/backface-visibility-hierarchical-transform.html
___________________________________________________________________

Added: svn:executable

Modified: trunk/Source/WebCore/ChangeLog (93386 => 93387)


--- trunk/Source/WebCore/ChangeLog	2011-08-19 04:51:38 UTC (rev 93386)
+++ trunk/Source/WebCore/ChangeLog	2011-08-19 05:44:52 UTC (rev 93387)
@@ -1,3 +1,32 @@
+2011-08-18  Shawn Singh  <shawnsi...@chromium.org>
+
+        Computing screen-space transform for LayerChromium and CCLayerImpl
+        https://bugs.webkit.org/show_bug.cgi?id=66114
+
+        Added a data member to LayerChromium and CCLayerImpl that holds
+        the screen-space transform.   The transform is computed in
+        calculateDrawTransformsAndVisibility(), which is used during
+        updating (LayerChromium) and drawing (CCLayerImpl).
+
+        Also fixed a FIXME in LayerRendererChromium::drawLayer, which
+        was not computing the entire hierarchy of transforms to determine
+        back-face visibility.  Now it simply uses the world space transform.
+
+        Reviewed by James Robinson.
+
+        Test: compositing/backface-visibility-hierarchical-transform.html
+
+        * platform/graphics/chromium/LayerChromium.h:
+        (WebCore::LayerChromium::screenSpaceTransform):
+        (WebCore::LayerChromium::setScreenSpaceTransform):
+        * platform/graphics/chromium/LayerRendererChromium.cpp:
+        (WebCore::LayerRendererChromium::updateLayers):
+        (WebCore::LayerRendererChromium::drawLayersInternal):
+        (WebCore::LayerRendererChromium::drawLayer):
+        * platform/graphics/chromium/cc/CCLayerImpl.h:
+        (WebCore::CCLayerImpl::screenSpaceTransform):
+        (WebCore::CCLayerImpl::setScreenSpaceTransform):
+
 2011-08-18  Ben Wells  <benwe...@chromium.org>
 
         [skia] -webkit-transform breaks -webkit-mask

Modified: trunk/Source/WebCore/platform/graphics/chromium/LayerChromium.h (93386 => 93387)


--- trunk/Source/WebCore/platform/graphics/chromium/LayerChromium.h	2011-08-19 04:51:38 UTC (rev 93386)
+++ trunk/Source/WebCore/platform/graphics/chromium/LayerChromium.h	2011-08-19 05:44:52 UTC (rev 93387)
@@ -206,6 +206,8 @@
     void setTargetRenderSurface(RenderSurfaceChromium* surface) { m_targetRenderSurface = surface; }
     const TransformationMatrix& drawTransform() const { return m_drawTransform; }
     void setDrawTransform(const TransformationMatrix& matrix) { m_drawTransform = matrix; }
+    const TransformationMatrix& screenSpaceTransform() const { return m_screenSpaceTransform; }
+    void setScreenSpaceTransform(const TransformationMatrix& matrix) { m_screenSpaceTransform = matrix; }
     const IntRect& drawableContentRect() const { return m_drawableContentRect; }
     void setDrawableContentRect(const IntRect& rect) { m_drawableContentRect = rect; }
 
@@ -298,6 +300,7 @@
     IntRect m_scissorRect;
     RenderSurfaceChromium* m_targetRenderSurface;
     TransformationMatrix m_drawTransform;
+    TransformationMatrix m_screenSpaceTransform;
     IntRect m_drawableContentRect;
 
     String m_name;

Modified: trunk/Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp (93386 => 93387)


--- trunk/Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp	2011-08-19 04:51:38 UTC (rev 93386)
+++ trunk/Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp	2011-08-19 05:44:52 UTC (rev 93387)
@@ -130,7 +130,7 @@
 // Recursively walks the layer tree starting at the given node and computes all the
 // necessary transformations, scissor rectangles, render surfaces, etc.
 template<typename LayerType, typename RenderSurfaceType, typename LayerSorter>
-void calculateDrawTransformsAndVisibility(LayerType* layer, LayerType* rootLayer, const TransformationMatrix& parentMatrix, Vector<RefPtr<LayerType> >& renderSurfaceLayerList, Vector<RefPtr<LayerType> >& layerList, LayerSorter* layerSorter, int maxTextureSize)
+void calculateDrawTransformsAndVisibility(LayerType* layer, LayerType* rootLayer, const TransformationMatrix& parentMatrix, const TransformationMatrix& fullHierarchyMatrix, Vector<RefPtr<LayerType> >& renderSurfaceLayerList, Vector<RefPtr<LayerType> >& layerList, LayerSorter* layerSorter, int maxTextureSize)
 {
     typedef Vector<RefPtr<LayerType> > LayerList;
     // Compute the new matrix transformation that will be applied to this layer and
@@ -173,6 +173,10 @@
     FloatRect layerRect(-0.5 * layer->bounds().width(), -0.5 * layer->bounds().height(), layer->bounds().width(), layer->bounds().height());
     IntRect transformedLayerRect;
 
+    // fullHierarchyMatrix is the matrix that transforms objects between screen space (except projection matrix) and the most recent RenderSurface's space.
+    // nextHierarchyMatrix will only change if this layer uses a new RenderSurface, otherwise remains the same.
+    TransformationMatrix nextHierarchyMatrix = fullHierarchyMatrix;
+
     // FIXME: This seems like the wrong place to set this
     layer->setUsesLayerScissor(false);
 
@@ -214,6 +218,9 @@
         layerOriginTransform.translate3d(-0.5 * bounds.width(), -0.5 * bounds.height(), 0);
         renderSurface->setOriginTransform(layerOriginTransform);
 
+        // Update the aggregate hierarchy matrix to include the transform of the newly created RenderSurface.
+        nextHierarchyMatrix.multiply(layerOriginTransform);
+
         // The render surface scissor rect is the scissor rect that needs to
         // be applied before drawing the render surface onto its containing
         // surface and is therefore expressed in the parent's coordinate system.
@@ -262,6 +269,14 @@
         }
     }
 
+    // Note that at this point, layer->drawTransform() is not necessarily the same as local variable drawTransform.
+    // layerScreenSpaceTransform represents the transform between layer space (in pixels) and screen space.
+    // So we do not include projection P or scaling transform S (see comments above that describe P*M*S).
+    TransformationMatrix layerScreenSpaceTransform = nextHierarchyMatrix;
+    layerScreenSpaceTransform.multiply(layer->drawTransform());
+    layerScreenSpaceTransform.translate3d(-0.5 * bounds.width(), -0.5 * bounds.height(), 0);
+    layer->setScreenSpaceTransform(layerScreenSpaceTransform);
+
     if (layer->renderSurface())
         layer->setTargetRenderSurface(layer->renderSurface());
     else {
@@ -307,7 +322,7 @@
 
     for (size_t i = 0; i < layer->children().size(); ++i) {
         LayerType* child = layer->children()[i].get();
-        calculateDrawTransformsAndVisibility<LayerType, RenderSurfaceType, LayerSorter>(child, rootLayer, sublayerMatrix, renderSurfaceLayerList, descendants, layerSorter, maxTextureSize);
+        calculateDrawTransformsAndVisibility<LayerType, RenderSurfaceType, LayerSorter>(child, rootLayer, sublayerMatrix, nextHierarchyMatrix, renderSurfaceLayerList, descendants, layerSorter, maxTextureSize);
 
         if (child->renderSurface()) {
             RenderSurfaceType* childRenderSurface = child->renderSurface();
@@ -605,7 +620,7 @@
 
     {
         TRACE_EVENT("LayerRendererChromium::updateLayers::calcDrawEtc", this, 0);
-        calculateDrawTransformsAndVisibility<LayerChromium, RenderSurfaceChromium, void*>(rootLayer, rootLayer, identityMatrix, renderSurfaceLayerList, rootRenderSurface->layerList(), 0, m_maxTextureSize);
+        calculateDrawTransformsAndVisibility<LayerChromium, RenderSurfaceChromium, void*>(rootLayer, rootLayer, identityMatrix, identityMatrix, renderSurfaceLayerList, rootRenderSurface->layerList(), 0, m_maxTextureSize);
     }
 
 #ifndef NDEBUG
@@ -737,7 +752,7 @@
 
     {
         TRACE_EVENT("LayerRendererChromium::drawLayersInternal::calcDrawEtc", this, 0);
-        calculateDrawTransformsAndVisibility<CCLayerImpl, CCRenderSurface, CCLayerSorter>(rootDrawLayer, rootDrawLayer, identityMatrix, renderSurfaceLayerList, m_defaultRenderSurface->layerList(), &m_layerSorter, m_maxTextureSize);
+        calculateDrawTransformsAndVisibility<CCLayerImpl, CCRenderSurface, CCLayerSorter>(rootDrawLayer, rootDrawLayer, identityMatrix, identityMatrix, renderSurfaceLayerList, m_defaultRenderSurface->layerList(), &m_layerSorter, m_maxTextureSize);
     }
 
     // The GL viewport covers the entire visible area, including the scrollbars.
@@ -1013,18 +1028,11 @@
     } else
         GLC(m_context.get(), m_context->disable(GraphicsContext3D::SCISSOR_TEST));
 
+    // The layer should not be drawn if (1) it is not double-sided and (2) the back of the layer is facing the screen.
+    // This second condition is checked by computing the transformed normal of the layer.
     if (!layer->doubleSided()) {
-        // FIXME: Need to take into account the cumulative render surface transforms all the way from
-        //        the default render surface in order to determine visibility.
-        TransformationMatrix combinedDrawMatrix;
-        if (layer->targetRenderSurface()) {
-            combinedDrawMatrix = layer->targetRenderSurface()->drawTransform();
-            combinedDrawMatrix.multiply(layer->drawTransform());
-        } else
-            combinedDrawMatrix = layer->drawTransform();
-
         FloatRect layerRect(FloatPoint(0, 0), FloatSize(layer->bounds()));
-        FloatQuad mappedLayer = combinedDrawMatrix.mapQuad(FloatQuad(layerRect));
+        FloatQuad mappedLayer = layer->screenSpaceTransform().mapQuad(FloatQuad(layerRect));
         FloatSize horizontalDir = mappedLayer.p2() - mappedLayer.p1();
         FloatSize verticalDir = mappedLayer.p4() - mappedLayer.p1();
         FloatPoint3D xAxis(horizontalDir.width(), horizontalDir.height(), 0);

Modified: trunk/Source/WebCore/platform/graphics/chromium/cc/CCLayerImpl.h (93386 => 93387)


--- trunk/Source/WebCore/platform/graphics/chromium/cc/CCLayerImpl.h	2011-08-19 04:51:38 UTC (rev 93386)
+++ trunk/Source/WebCore/platform/graphics/chromium/cc/CCLayerImpl.h	2011-08-19 05:44:52 UTC (rev 93387)
@@ -158,6 +158,8 @@
 
     const TransformationMatrix& drawTransform() const { return m_drawTransform; }
     void setDrawTransform(const TransformationMatrix& matrix) { m_drawTransform = matrix; }
+    const TransformationMatrix& screenSpaceTransform() const { return m_screenSpaceTransform; }
+    void setScreenSpaceTransform(const TransformationMatrix& matrix) { m_screenSpaceTransform = matrix; }
     const IntRect& drawableContentRect() const { return m_drawableContentRect; }
     void setDrawableContentRect(const IntRect& rect) { m_drawableContentRect = rect; }
 
@@ -226,6 +228,7 @@
     float m_debugBorderWidth;
 
     TransformationMatrix m_drawTransform;
+    TransformationMatrix m_screenSpaceTransform;
 
     // The scissor rectangle that should be used when this layer is drawn.
     // Inherited by the parent layer and further restricted if this layer masks

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