Problem: Projector texture (artifacts / repeating)

Graphics Shaders & Materials
1

EDIT: Solution

I got a projector set up with a shader to do additive blending (its a customized blob-shadow shader), alpha-only falloff texture and RGBA cookie texture. It all works with just a minor problem: The projected texture repeats infinately outside the projection cone.

Here’s a pic:

Whats going on?

Here is the shader code:

Shader "FX/Projector Add" { 
	Properties {
		_ShadowTex ("Cookie", 2D) = "gray" { TexGen ObjectLinear }
		_FalloffTex ("FallOff", 2D) = "white" { TexGen ObjectLinear	}
	}

	Subshader {
		Pass {
			ZWrite Off
			// Offset -1, -1

			Fog { Color (1, 1, 1) }
			AlphaTest Greater 0
			ColorMask RGB
			Blend One One
			SetTexture [_ShadowTex] {
				combine texture, ONE - texture
				Matrix [_Projector]
			}
			SetTexture [_FalloffTex] {
				constantColor (0,0,0,0)
				combine previous lerp (texture) constant
				Matrix [_ProjectorClip]
			}
		}
	}
}

Any ideas?

2

You presumably just need to select the offending texture in the Project pane and set it to Clamp instead of Repeat in the inspector.

3

That almost did it, yet there are still some odd artifacts. I tried painting a black edge around the projected texture… that dimmed the streaks a bit but didn’t remove them entirely. Also the streaks in the projector’s YZ plane aren’t going away.

4

Clamping stops the texture at the edge pixels, then stretches those pixels off in all directions. Make sure your texture has a single colour border around it to avoid that.

EDIT: oops, I see you tried that. What about a thicker border?

EDIT 2: does it help if you remove AlphaTest Greater 0?

1 Like
5

It helps to make the border wider and set aniso higher.

Leaves only the artifacts in the YZ plane.

6

Turn off mipmaps in the import settings? I vaugley remember Nicholas giving me this advice and it worked great.
HTH
AC

Edit: or it was Turn off border mipmaps-try that

7

Thanks, now it works.

So for all who come after me here is a summary:

To make a custom Projector:

  • Set all involved textures to “Clamp”
  • Depending on your blend mode, draw a white/black/transparent border around your texture. 1+ pixels wide.
  • import the textures with “Border Mipmaps ON”.
8

I think ideally you’d still want mipmaps, so try the turn off border mipmaps option. Hows that looking?
AC