Depth masking a sprite?

Questions
1

I’m wondering if there are any clever hacks for depth masking a sprite with alpha values. View the below screenshot:

pillarsandconcrete
pillarsandconcrete510×937 492 KB

The player has a box where it’s clearing the pillar behind it. If I don’t apply depth testing the player appears behind the model. I’m thinking the best way would be to somehow define a background color and remove it somehow via a shader but I’m still inexperienced in this field. Has anyone encountered this type of rendering conundrum before?

Thanks if anyone has some sage advise :slight_smile:

2 Likes
2

Try to add this to the box’s fragment shader (.fp):

if (color.a < 0.01) {
    discard;
}
3

That’s slow on GPUs with tiled renderers (like on mobile)

2 Likes
4

Yes. If @Epitaph64 uses it for a small sprite, the performance will be OK :slight_smile:

I like this note from Mali GPU best practises guide:

For example, we tell you not to use discard in fragment shaders. It is inevitable that there are cases where you must use a feature that we do not recommend using, because the feature is required for some algorithms. Therefore, do not feel restricted by our advice to never use a feature. However, always keep in mind that there could be an underlying performance risk.

2 Likes
5

Thanks for the info! I’ll bear that in mind. I think at this point I’ll likely either go with all sprites or all models however for the performance benefits. I’m still trying to figure out the model rendering for HTML5/Android however.