Seems discard in wgsl does't work with bevy? or there's something others make the output different as i expect

[Ahuang0107]

I implement the sprite mask feature with stencil test in pure wgpu(version = "23.0.1"), i use a sprite mask shader, when texture alpha is zero, it will discard, so it won't write into stencil texture, the effect like this,

but when i implement same logic in bevy, and use a rgba image as sprite mask, the whole image area applyed mask, not just opaque pixel area. as if discard not work.

[Ahuang0107]

I only know a little bit about the MainTransparentPass2d pipeline, not everything. Is there anyone who can provide some help?

[Ahuang0107]

never mind, turn out i deleted unused VertexInput variable in sprite_mask.wgsl, but sprite.wgsl and sprite_mask.wgsl both using same instance buffer struct，so the mapping relationship is wrong, vertex input get wrong i_uv_offset_scale make uv wong.