Fix some calculation errors for ps_split_composite and make_polygon.

webrender/res/ps_split_composite.glsl

@@ -38,11 +38,15 @@ void main(void) {
     CompositeInstance ci = fetch_composite_instance();
     SplitGeometry geometry = fetch_split_geometry(ci.user_data0);
     AlphaBatchTask src_task = fetch_alpha_batch_task(ci.src_task_index);
+    AlphaBatchTask dest_task = fetch_alpha_batch_task(ci.render_task_index);
+
+    vec2 dest_origin = dest_task.render_target_origin -
+                       dest_task.screen_space_origin;
 
     vec3 world_pos = bilerp(geometry.points[0], geometry.points[1],
                             geometry.points[3], geometry.points[2],
                             aPosition.y, aPosition.x);
-    vec4 final_pos = vec4(world_pos.xy * uDevicePixelRatio, ci.z, 1.0);
+    vec4 final_pos = vec4((world_pos.xy + dest_origin) * uDevicePixelRatio, ci.z, 1.0);
 
     gl_Position = uTransform * final_pos;
 

webrender/src/frame_builder.rs

@@ -8,7 +8,7 @@ use api::{DeviceIntPoint, DeviceIntRect, DeviceIntSize, DeviceUintRect, DeviceUi
 use api::{ExtendMode, FIND_ALL, FilterOp, FontInstance, FontRenderMode};
 use api::{GlyphInstance, GlyphOptions, GradientStop, HitTestFlags, HitTestItem, HitTestResult};
 use api::{ImageKey, ImageRendering, ItemRange, ItemTag, LayerPoint, LayerPrimitiveInfo, LayerRect};
-use api::{LayerSize, LayerToScrollTransform, LayerVector2D, LayoutVector2D, LineOrientation};
+use api::{LayerPixel, LayerSize, LayerToScrollTransform, LayerVector2D, LayoutVector2D, LineOrientation};
 use api::{LineStyle, LocalClip, POINT_RELATIVE_TO_PIPELINE_VIEWPORT, PipelineId, RepeatMode};
 use api::{ScrollSensitivity, Shadow, TileOffset, TransformStyle};
 use api::{WorldPixel, WorldPoint, YuvColorSpace, YuvData, device_length};
@@ -1731,6 +1731,7 @@ impl FrameBuilder {
                 stacking_context.isolated_items_bounds = stacking_context
                     .isolated_items_bounds
                     .union(&prim_geom.local_rect);
+                stacking_context.has_any_primitive = true;
 
                 profile_counters.visible_primitives.inc();
             }
@@ -1739,12 +1740,22 @@ impl FrameBuilder {
         true //visible
     }
 
-    fn handle_pop_stacking_context(&mut self, screen_rect: &DeviceIntRect) {
+    fn handle_pop_stacking_context(
+        &mut self,
+        screen_rect: &DeviceIntRect,
+        clip_scroll_tree: &ClipScrollTree) {
         let stacking_context_index = self.stacking_context_stack.pop().unwrap();
 
         let (bounding_rect, is_visible, is_preserve_3d, reference_id, reference_bounds) = {
             let stacking_context =
                 &mut self.stacking_context_store[stacking_context_index.0];
+            if !stacking_context.has_any_primitive {
+                stacking_context.isolated_items_bounds = stacking_context.children_sc_bounds;
+            } else if stacking_context.isolation != ContextIsolation::Items {
+                stacking_context.isolated_items_bounds = stacking_context
+                    .isolated_items_bounds
+                    .union(&stacking_context.children_sc_bounds);
+            }
             stacking_context.screen_bounds = stacking_context
                 .screen_bounds
                 .intersection(screen_rect)
@@ -1763,9 +1774,21 @@ impl FrameBuilder {
         if let Some(ref mut parent_index) = self.stacking_context_stack.last_mut() {
             let parent = &mut self.stacking_context_store[parent_index.0];
             parent.screen_bounds = parent.screen_bounds.union(&bounding_rect);
+            let child_bounds = reference_bounds.translate(&-parent.reference_frame_offset);
+            let frame_node = clip_scroll_tree
+                .nodes
+                .get(&reference_id)
+                .unwrap();
+            let local_transform = match frame_node.node_type {
+                NodeType::ReferenceFrame(ref info) => info.transform,
+                _ => LayerToScrollTransform::identity(),
+            };
+            let transformed_bounds = local_transform
+                .with_destination::<LayerPixel>()
+                .transform_rect(&child_bounds);
+            parent.children_sc_bounds = parent.children_sc_bounds.union(&transformed_bounds);
             // add children local bounds only for non-item-isolated contexts
             if !is_preserve_3d && parent.reference_frame_id == reference_id {
-                let child_bounds = reference_bounds.translate(&-parent.reference_frame_offset);
                 parent.isolated_items_bounds = parent.isolated_items_bounds.union(&child_bounds);
             }
             // Per-primitive stacking context visibility checks do not take into account
@@ -1917,7 +1940,7 @@ impl FrameBuilder {
                     );
                 }
                 PrimitiveRunCmd::PopStackingContext => {
-                    self.handle_pop_stacking_context(screen_rect);
+                    self.handle_pop_stacking_context(screen_rect, clip_scroll_tree);
                 }
             }
         }

webrender/src/tiling.rs

@@ -1606,6 +1606,12 @@ pub struct StackingContext {
     /// This is a temporary hack while we don't support subpixel AA
     /// on transparent stacking contexts.
     pub allow_subpixel_aa: bool,
+
+    /// Indicate that if any pritimive contained in this stacking context.
+    pub has_any_primitive: bool,
+
+    /// Union of all stacking context bounds of all children.
+    pub children_sc_bounds: LayerRect,
 }
 
 impl StackingContext {
@@ -1638,6 +1644,8 @@ impl StackingContext {
             is_visible: false,
             is_backface_visible,
             allow_subpixel_aa,
+            has_any_primitive: false,
+            children_sc_bounds: LayerRect::zero(),
         }
     }
 

wrench/reftests/split/intermediate-1-ref.yaml

@@ -0,0 +1,12 @@
+---
+root:
+  items:
+    - type: rect
+      bounds: 8 36 100 100
+      color: green
+    - type: rect
+      bounds: 108 36 100 100
+      color: blue
+    - type: rect
+      bounds: 208 36 100 100
+      color: yellow

wrench/reftests/split/intermediate-1.yaml

@@ -0,0 +1,38 @@
+---
+root:
+  items:
+    - type: rect
+      bounds: 8 36 300 100
+      color: red
+    - type: stacking-context
+      transform-style: preserve-3d
+      transform: translate(8, 36, 0)
+      items:
+        - type: stacking-context
+          transform-style: preserve-3d
+          items:
+            - type: rect
+              bounds: 0 0 100 100
+              color: green
+        - type: stacking-context # flat, intermediate surface
+          items:
+            - type: stacking-context
+              transform: translate(100, 0, 0)
+              transform-style: preserve-3d
+              items:
+                - type: stacking-context
+                  transform-style: preserve-3d
+                  items:
+                    - type: rect
+                      bounds: 0 0 100 100
+                      color: blue
+                - type: stacking-context
+                  transform: translate(100, 0, 0)
+                  transform-style: preserve-3d
+                  items:
+                    - type: stacking-context
+                      transform-style: preserve-3d
+                      items:
+                        - type: rect
+                          bounds: 0 0 100 100
+                          color: yellow

wrench/reftests/split/intermediate-2.yaml

@@ -0,0 +1,34 @@
+---
+root:
+  items:
+    - type: rect
+      bounds: 8 36 300 100
+      color: red
+    - type: stacking-context
+      transform-style: preserve-3d
+      transform: translate(8, 36, 0)
+      items:
+        - type: stacking-context
+          transform-style: preserve-3d
+          items:
+            - type: rect
+              bounds: 0 0 100 100
+              color: green
+        - type: stacking-context
+          items:
+            - type: stacking-context
+              transform: translate(100, 0, 0)
+              items:
+                - type: rect
+                  bounds: 0 0 100 100
+                  color: blue
+                - type: stacking-context
+                  transform: translate(100, 0, 0)
+                  transform-style: preserve-3d
+                  items:
+                    - type: stacking-context
+                      transform-style: preserve-3d
+                      items:
+                        - type: rect
+                          bounds: 0 0 100 100
+                          color: yellow

wrench/reftests/split/reftest.list

@@ -3,4 +3,6 @@
 == nested.yaml nested-ref.yaml
 == nested-preserve3d-crash.yaml nested-preserve3d-crash.yaml
 == perspective-clipping.yaml perspective-clipping-ref.yaml
+== intermediate-1.yaml intermediate-1-ref.yaml
+== intermediate-2.yaml intermediate-1-ref.yaml
 #== cross.yaml cross-ref.yaml #TODO: investigate sub-pixel differences