Esoteric Software

[dragonikpl]

After few days of hard work and trying to grasp my head around Apple's Metal, I finally managed to integrate spine C runtime into SpriteKit framework! I based my code on cocos2d runtime, but rewrote it in Swift. Rendering is based on meshes that C runtime generates. Here's a demo running on iPhone X backed by SpriteKit



After I am happy with results and clean up my code, I will post source code to github (and add it to this thread).

[Nate]

Cool!

BTW, the dark outlines look like a PMA problem.

[dragonikpl]

I cannot grasp my head around PMA - I am getting those black borders around textures.

This is my blend mode for premultipliedAlpha flag set to true:

source alpha = .one
destination alpha = .oneMinusSourceAlpha
source color = .one
destination color = .oneMinusSourceAlpha

Blending operations are set to add.

Any ideas where to look why it doesn't work properly?


Rendering without PMA looks nice.

Zrzut ekranu 2020-01-27 o 18.09.38.png

[Nate]

Those blending modes look right for PMA. Those plus an atlas that was created with PMA should give you the correct results. Could it be something in your toolchain is wrecking your images? In the past, Apple tools have been known to apply PMA!

[plament]

Recently I've implemented Metal rendering using the C++ runtime and had some issues with PMA. Seems PMA is always applied on the textures when building on the device and is not when building on the Simulator. Here is my Metal blending setup:

pipelineStateDescriptor.colorAttachments[0].blendingEnabled = YES;
pipelineStateDescriptor.colorAttachments[0].rgbBlendOperation = MTLBlendOperationAdd;
pipelineStateDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperationAdd;
#if TARGET_IPHONE_SIMULATOR
pipelineStateDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorSourceAlpha;
#else
pipelineStateDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorOne;
#endif
pipelineStateDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactorSourceAlpha;
pipelineStateDescriptor.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactorOneMinusSourceAlpha;
pipelineStateDescriptor.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactorOneMinusSourceAlpha;

Also I needed to set MTKTextureLoaderOptionSRGB : @NO when loading the textures in my TextureLoader

[dragonikpl]

Thanks for a reply @plament, I applied your findings, but it is still rendering incorrectly. I had SRGB option set to NO.

[plament]

Have you tried to create the atlas without PMA enabled?

[hanover]

After I am happy with results and clean up my code, I will post source code to github (and add it to this thread).

Would you like to share you implementation?