Sign in to follow this  
shultays

is there a name for this algorithm? =)

Recommended Posts

shultays    187
I know this is a stupid question sorry about that. I am working on a scholl project, I implemented an algorithm for painting the terrain. I saw it first on tag, I tried something (very) similiar in my game. It is basically painting on texture of the model. Actually it creates a new texture for paint, and combines it with real texture while rendering. does this algorithm have a specific name? I couldn't find anything on Tag's webpage about it. and one from my project

Share this post


Link to post
Share on other sites
shultays    187
Quote:
Original post by phresnel
Are you talking about decals, maybe?


I am not sure what decal is, is it rendering a texture on a model? like rendering blood splashes on the walls?

it is not like that I think. I guess for decals, it renders the model first and after that it renders decals on the model. This method simply paints the texture.

For example



Ball has two texture, first one is its real texture and second one is paint texture. When it wants to paint something on ball, it uses UV coordinates to find which part of the paint texture it should paint and paint it. And while rendering the ball, it combines two textures while rendering model.

So painting scene does not create new entities for rendering, it just edits existing resources. So amount of painting does not increase the scene compexity

Share this post


Link to post
Share on other sites
Grafalgar    548
Are you doing this in a shader, or are you literally taking the two textures and combining them into a new texture, discarding the previous two and just using the new texture?

If you keep both textures in memory, and combine them using a shader or similar, then that's just multi-texturing. You can come up with neat effects like a cheap water, clouds, etc using multi-texturing :)

Share this post


Link to post
Share on other sites
shultays    187
Yes I am doing in shader but I am not talking rendering a model with more than 1 textures. I wanted to ask if there is a name for painting a model's texture (or another texture ad combining it with model texture) to paint actualt scene like in or my game.

I saw it on Tag, and one video on youtube, which was using source engine. I thought maybe it has a name and I can research about it and shot it in background section of report.

I guess it is too specific and simple to be a popular algorithm :)

Share this post


Link to post
Share on other sites
Mussi    4407
It involves multiple things. You ray cast the model, use barycentric coordinates to solve whether the point lies in the triangle. Use those coordinates to determine the uv-coordinates and use those to edit the paint texture.

Share this post


Link to post
Share on other sites
Hodgman    51222
Yeah it's a variation of decal mapping. I don't know if there's a standard name for it. We've used it before and just called it a decal, but we've got a few different decal systems so that gets confusing...
I've heard some people call it a procedural decal overlay, others calling it dynamic splatting, etc...

I'd just call it a dynamically updated overlay texture (that kind of explains what it is, I think).

Share this post


Link to post
Share on other sites
Hodgman    51222
Mussi's already touched on the main steps.

Normally each object has a "material" (Which can be shared between objects), a material might be made up of several textures (diffuse, normal map, etc).

With this "overlay" system, each object also gets a unique "overlay" texture (which belongs to the object, not to the shared material). To begin with, this texture starts out with a black alpha channel (i.e. it's invisible).

When something hits the object, you find the collision point, then you find the texture-coordinates for the collision point, which gives you a 2D position inside your overlay texture. You can then use this position to paint a "decal" in 2D onto the overlay (using render-to-texture techniques).

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this