~~##### # GFX 2019 work week

Interning positions?

(gw, kvark)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem best(TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

• > ##### - however, hit testing still is a problem (TODO: clarify)``

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

- we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify) just clarify

[]because its funny
right ?

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)##### - we intern sizes but not positions of clips and primitives

- gecko bakes the scroll offsets

- new API now allows us to ask for the scroll offsets and “unbake” them

- however, hit testing still is a problem (TODO: clarify)

- need getrelativetransform to be used consistently

- blocked on flattening rework (TODO: resolve)

Mix-blend rollback

TODO

CSS Shooter perf

TODO

Render task graph

(nical, gw, kvark)

Problem 1: a task is dependent on my multiple other tasks

Case: multiple drop shadows on the same text item

Opportunity: only downscale the text once, use for all shadow tasks

Note: render task cache can't be used, since it doesn't handle dependencies well (scheduling issue).

- solution: schedule the RT cache as late as possible

- when dependencies are in the texture cache, we'd need to render in a pass and blit back to the texture cache

Concern: render task rect rect allocation assumes that the source is in the previous pass.

- solution: blit contents of a task across passes

- schedule as late as possible

- retain some of the render task slices/rects as opposed to clearing

Blits are expensive:

- bounds are not tight

- the perf on Intel scales with the number of pixels we touch

TODO: check ARM/Mali for when the tiles are resolved:

- does it happen if the tile is unchanged?

- what if it was just cleared?

Motivation:

1. reduce redundant shadow tasks

2. remove "mark for saving"

3. SVG filters are expressed as graphs

Q: retain across frames?

A: currently, not retaining any shadow tasks

Q: debugging tools for RT graph resolver?

A: fun thing to write, given that the thing is fairly standalone

N: need tooling to find out the best scheduling off-line, compare with the run-time by the number of pixels

Current "best" strategy:

- ping-pong as current WR

- schedule late

Q: incremental deployment of the new alloctor?

1. first, integrate with existing behavior

2. enable for shadows and other things

3. play with strategies

Future:

1. Since texture array, sub-manage slices. Try work with slices, not rects.

2. Render pass as the whole render target, select the slice in VS.

3. Try identifying the 1:1 pass work, use sub-passes.

- tile cache memory limits? know how many mask slices are there

- can provide the whole frame as one giant render pass

Q: can we exploit the axises and auto-rotate things?

- would be good!

- segmentation solves the problem to some extent

- could also exploit the symmetry

Rounded corners optimizations:

- only render the corners into the mask

- exploit the symmetry

- more precise bounding/geometry to reduce fill rate

- can't apply the local clip rect in this case!

- quad tree subdivision (or a regular grid) - still draw rects

- can't multiply the clip mask (TODO: discuss)

Current PLS "optimization"

(gw, kvark, Gankro)

TODO

Flattening semantics

TODO

WebGPU integration

(kats, kvark)

Process of vendoring wgpu-rs:

- move into the tree

- improve the remote layer

- establish scripts to/from GitHub

Gecko will have 2 implementations as well, in the shape of different structs with the same virtual interface: local and remote. Differences are:

1. Client parameter in all functions of the remote layer

2. Swapchain integration (unknown on Gecko side)

3. Pass dependencies collection in the remote layer

Q: how do we reduce the JS calls in client apps?

Moving into Gecko:

1. copy into tree as "gfx/webgpu"

2. connect it into libgkrust's Cargo.toml and lib.rs

3. Run ./mach vendor rust, check complains about licensing. This will add dependencies to thirdparty/rust, make sure it looks sane

4. add build option "–enable-webgpu" similar to WR here. make the libgkrust integration stuff from step 2 behind a feature flag controlled by the build option

5. To add a taskcluster job, copy and modify the existing webrender standalone jobs such as this one - copy it into a new taskcluster/ci/webgpu/kind.yml file. You won't need the wrench-deps stuff, just run cargo build in the gfx/webgpu folder

WebRender architecture overview

(gw)

Display Lists:

1. - Items

- text

- box shadowssssss

- image

- Stacking contexts

- filtersś

- Clip chains

- Reference frames

Scene ("model"):

- picture tree

1. - spatial tree

1. - clip chains

1.

1. Q: "scene" term vs WR capturing

1. Q: internation? (see picture caching)

1. Q: tile caching?

| Column 1 | Column 2 | Column 3 |

| –––– | –––– | –––– |

| Text | Text | Text |

can be scrolled around

Frame ("view"):

- update spatial tree

- update picture tree

- update visibility

- update primitives

- generate render tasks

- assign passes

- batch

Submit:

- apply resource updates

- for each pass

- for each layer

- bind resources

- draw

Picture caching

Q: stuff moved but not marked as changed by the debug overlay?

A: could be fixed-position element that isn't cached, drawn on top

Interning key:

1. item itself

2. clipping

3. transform

4. animated properties (e.g. opacity)

Picture = (prim uuid, uuid, uuid, ..) but

Tiles 1024x256. Identifying the dirty regions and updating them with a scissor rect.

Q: what happens with complex regions?

A: draw the whole thing

- should set the Z on tiles to reject the pixels over the valid tiles (TODO: verify)

- blog-post-like pages are still the bad case

Q: tile coordinate space?

A: world. If stuff is scrolled, the positions are adjusted, so we get the same world results.

Q: how does the valid content gets into the new frame

A: copied through the texture cache

~~~~**