Prevent spawned decal from projecting on opposite of a mesh?

bathorysthroat · November 25, 2019, 1:10am

Hi, I’ve made a blood decal that gets spawned at the location of a particle collision, to cause a blood splatter effect. However, when the decal hits a wall mesh the effect is shown on both sides of the wall. I want the decal to only show on the side of the wall which the particle collides with. Is there any way of doing this to keep the spawned decal only showing on the correct side?

This is how I spawn the decal at the colliding location:

Here is the result:

The front side of the wall.

The back side of the wall.

The material used for the decal blend mode is:
DBuffer Translucent color, Normal, Roughness.

Any advice on how I can fix this?

Thanks!

TRI99ER · November 26, 2019, 3:39pm

Is your wall zero thickness?

bathorysthroat · November 26, 2019, 4:36pm

No, I believe they are a thickness of 10. Why do you ask?

bathorysthroat · November 27, 2019, 1:04am

Ok that’s what I did and the decal no longer clips through the wall but because I have my particles spawning decals at the location of the particle collision the changing of the X value is causing my decal to look thin and stretched. :I

Psych1809 · November 27, 2019, 1:26am

Mind posting another picture of the new blueprint?

Psych1809 · November 27, 2019, 12:13am

The Decal Size is to big and is projecting trough the wall. Try to put the Random Float in Range in the Z and Y in a Make Vector node and set the X to a smaller amount.

bathorysthroat · November 28, 2019, 2:10am

Here you go, not much has changed set the X to 1 only.

Psych1809 · November 28, 2019, 11:24am

Change the value from the RotateFromXVector node. Use the Normal instead of the Direction.

You can also set some random values to the Make Rotators Y and Z to add some variety.

bathorysthroat · November 28, 2019, 10:59pm

Thanks, I actually figured that bit out last night. Now my only issue is that the blood that hits both the floor and the wall tends to leak under the wall model and on to the other side because it’s recently projecting on to the floor first.

Here’s kind of a dumb little example I mocked up quick to explain what I need to happen if possible:

Is it at all possible to force the decal to bend to the angle of each object it lands on? So that shows as a splat at the point where it makes contact and goes no farther, bending to the shape of both the floor and wall models. Maybe then preventing the decal from appearing on the floor on the side of the room it was not spawned in. I hope that makes sense.

I know that postal 2 doses this all though that was made in UDK 2 or 3 I believe,

So if this can’t be achieved then my blood system will always show under the walls and on the other side instead of only showing on the surface faces touched. It would be a real shame as it would break any believability and thus look fake. any ideas? I wouldn’t even know where to begin.

Psych1809 · November 29, 2019, 12:17pm

Not sure how I would do that. But you could start by looking at Decal materials and try to find another solution to prevent the decal from projecting through the wall. Link

I found this Feature Request where he asked about the bending decals.