jMonkeyEngine.org

Update:
- “(Single)TextureProjectorRenderer” is default again. I said multi would be faster, but that was a mistake.
- Some refactoring:
— “ProjectiveTextureMapping1pass” -> “ProjectiveMultiTextureMapping”
— “TextureProjectorRenderer1pass” -> “MultiTextureProjectorRenderer”
- Z-fighting fix “setPolyOffset(-0.1f, -0.1f)” by default
- Different CombineMethods in “MultiTextureProjectorRenderer”
- Bugfixes
- ul and li don’t work btw

Snapshot: ProjectiveTextureMapping-2012-03-15.zip

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I wrote a post processor which does Projective Texture Mapping. See also this paper by nVidia. It is related to the thread Projected Texture on this forum.

Features:
- Can project an arbitrary number of textures onto scene geometry
- You can choose which geometry shall be affected (GeometryList)
- Perspective and parallel projection
- Back projection and backside projection fixed
- Fall off distance and fall off power to limit the projection

Video demonstration of latest version (note the rune is just projected onto one geometry):

Motivation:
A use case of projected textures are targeting circles and ground effects known from popular MMOs by BlizZzard and Buy-o-ware. It can also be used to simulate the light cone of a flashlight/torch.

The code including a test application can be checked out here:
http://code.google.com/p/survivor-jme/source/browse/#svn%2Ftrunk%2FProjectiveTextureMapping

Please note that this is work in progress. It might change frequently and it will surely have bugs.

Future work:
I’m planning to write a shader that can do all in one pass like this:

uniform vec3 m_ProjectorLocation[NUM_PROJECTORS];
uniform mat4 m_ProjectorViewProjectionMatrix[NUM_PROJECTORS];

for (int i = 0; i < NUM_PROJECTORS; i++)
{
  vec3 pl = m_ProjectorLocation[i];
  mat4 pm = m_ProjectorViewProjectionMatrix[i];

  // process an arbitrary number of projectors in a single pass
}

I don’t know if this makes sense, though. I can’t yet estimate performance bottlenecks.

I’d also love to see this in the GL1Renderer.

Thanks very much for this contribution! I am sure many people will be happy to see this

This is really cool!

I am currently trying to apply it as a flashlight in a game I’m messing around with.

Is it possible in the current state to limit the projection distance, possibly with some kind of degradation.

And is it possible mark objects as cast and receive shadow of the projection?. In effect having geometry block parts of the projection for surfaces behind it?

I made some optimizations, especially to “TextureProjectorRenderer1pass” which can now handle an arbitrary number of projectors by using multiple passes with up to 8 projectors per pass (“1pass” is a bit misleading). Since it’s ~3.3x faster than “TextureProjectorRenderer”, “TestProjectiveTextureMapping1pass” has become the new default run target of the project.

Unfortunately, these decals will not work with displacement / parallax mapped surfaces. Does anyone have an idea how to handle that?

@survivor could you just run the displacement/parallax methods after the projective texturing?

@survivor said:

Edit: I think the way to do this is a pre-pass that combines the decal / projective texture and the diffuse texture and replaces the diffuse texture of the original material. This way, one could even create decals that have normal and parallax map themself. This would enable bumped and parallaxed decals on bumped and parallaxed surfaces without altering the material / shader (it is altered on-the-fly). I don’t know if it’s doable and the performance might be horrible due to many texture swiches, but the idea is interesting.

@survivor That’s kinda what I was getting at. Shaders definitely aren’t my forte however…. I was assuming that if you projected the texture onto a flat surface then the later pass of the parallax shader would already have the appropriately colored frag information. The stuff that I have read isn’t very clear on this.

Thanks! I’m currently fixing bugs and doing some cleanup. I’ll let you know when I’m done and there’s an initial version that can be put into another repository. My google code repository will stay my playground for preliminary version.

great! you are a real shader guru. nehon guru propably will accept other guru