solved How to change blend equation?

[leht]

Hello,

Could you tell me how to use the blend equation other than GL_FUNC_ADD and GL_FUNC_SUBTRACT? For example I want to use the GL_MIN and GL_MAX.

I've read about the Material.alphaMode property but cannot find the suitable option for my case.

[kcoley]

Hello @leht, is this doc useful?: https://doc.babylonjs.com/how_to/how_to_use_blend_modes

[leht]

@kcoley It only tells about blend mode but doesn't tell about blend equation. I need a way to change blend equation from GL_FUNC_ADD to GL_MAX / GL_MIN. https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glBlendEquation.xhtml

[leht]

I find the function setAlphaEquationParameters(rgb: number, alpha: number) in class Engine but it isn't called anywhere. Could you call it in the setAlphaMode function in some way?

[kcoley]

@leht gotcha, you can probably call setAlphaEquationParameters with an onBindObservable call on the material:

 

let mat = new BABYLON.StandardMaterial("standard", scene);
mat.onBindObservable = function() {
    engine.setAlphaEquationParameters(...); // pass parameters here
}

 

[leht]

Thank you very much! It works.

A bit correcting: we should call engine._alphaState.setAlphaEquationParameters(...)

Do you think we need some clearer way to customize blend mode (blend equation, blend func parameters)? I think Material.alphaMode  is easy to use but not enough. And do the trick like above seems quite ugly ...

[Guest]

We could probably add more options here:

https://github.com/BabylonJS/Babylon.js/blob/master/src/Engine/babylon.engine.ts#L3936

Feel free to do a PR to add more modes! I will merge it

[leht]

Thanks @Deltakosh,

Of course I can do a PR for some more options, but I think there will be not many people here need them, since those options are only for some special needs. (I'm working in the MIP / MinIP feature of a DICOM viewer medical application, not a video game.)

Recently I worked with Three JS & they have a customBlending mode with separated methods for customizing blend equation & blend function parameters (https://threejs.org/docs/#api/en/constants/CustomBlendingEquations).

Do you think we need a similar way for easier customization?

[Guest]

yes definitely something we need