DisplayObject blend mode tracking issue

[Herschel]

Desktop:

• Normal
• Layer
• Add
• Alpha
• Darken
• Difference
• Erase
• Hardlight
• Invert
• Lighten
• Multiply
• Overlay
• Screen
• Subtract
• Shader (Pixel Bender)

Web canvas:

• Normal
• Layer
• Add
• Alpha
• Darken
• Difference
• Erase
• Hardlight
• Invert
• Lighten
• Multiply
• Overlay
• Screen
• Subtract
• Shader (Pixel Bender)

ActionScript:

• DisplayObject.blendMode
• DisplayObject.blendShader

[wizzwizz4]

Some of those (Screen, I think, and some others) don't have a single definition. It'll take some snooping, and maybe reverse-engineering, to figure out which algorithm they're using.

[karliss]

AS3 documentation https://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/DisplayObject.html#blendMode has a bit more information than swf format specification.

[Herschel]

All of the non-normal blend modes cause the display object to have "cache as bitmap" behavior, where the display object is rendered into an offscreen render target first, and then this buffer is drawn onto the stage. Same with all the filters. In fact, Layer blend mode is just Normal with the offscreen buffer behavior.

So the first step is to implement render target functionality in RenderBackend. It's already there for masking on web, but needs to be added to desktop.

[ThisFlyingPotato]

Lacks blend effect

Screenshots

First is how it is with Ruffle, second is how it is supposed to be.

OS : Win7-64bits
Both on the Chrome Extension and standalone
On ruffle-nightly-2021_05_01

Ps : link of the game (you can test the blend by pressing space or going at the room all the way up, and pressing E next to the sword)
https://fr.y8.com/games/pandoras_seed

[relrelb]

A description for each blend mode: https://www.adobe.com/content/dam/acom/en/devnet/pdf/pdfs/pdf_reference_archives/blend_modes.pdf

Seems that Adobe used the same formulas from the PDF spec.

[gskt17]

All of the non-normal blend modes cause the display object to have "cache as bitmap" behavior, where the display object is rendered into an offscreen render target first, and then this buffer is drawn onto the stage. Same with all the filters. In fact, Layer blend mode is just Normal with the offscreen buffer behavior.

So the first step is to implement render target functionality in RenderBackend. It's already there for masking on web, but needs to be added to desktop.

So...has this functionality been added for desktop yet? What is our plan for implementing this feature?

[torokati44]

Well, I wouldn't call it much of a plan, just my ramblings from a while ago: #4288

[Lord-McSweeney]

Blend modes have been implemented by #8262, and will appear in web after #9134 is merged.

[Kippykip]

Looks like there is definitely an improvement!
Although "Clown Killer 2" still seems to have some other blending related display issues

[Lord-McSweeney]

The only one left unimplemented here is blendShader (BlendMode.SHADER).

[Kippykip]

Excellent progress! :D
There are some minor glitches with the blur but it is looking very close to the original game!
The health bar finally visibly goes down too!

I think Clown Killer 2 is a great testing SWF for special GFX effects, since it uses a lot of blends, uses text outline glow extensively, and has those health shade bar effects (eggy easter also used it)

[Lord-McSweeney]

Finally closed by #12238.

[Kippykip]

Amazing!!! Pretty much perfect now under ruffle.