Culling pixels

[Rekindled Phoenix]

What would be the best way, using Leadwerks to accomplish this? Is it possible with the current engine?

 

This is clearly hypothetical, and thought it would make for an interesting topic.

Rendering Wounds in L4D2 (Warning: grotesque images of dismembered zombies follow this link)

[Josh]

When they say they are using an ellipsoid to cull pixels, what they mean is they are giving the shader an equation for that shape and discarding pixels in a mathematic test that checks if their position is inside the volume. So it's perfectly possible without interfering with the rest of the rendering pipeline.

 

The gore in L4D2 is pretty extreme, although I love the game.

[Rekindled Phoenix]

When they say they are using an ellipsoid to cull pixels, what they mean is they are giving the shader an equation for that shape and discarding pixels in a mathematic test that checks if their position is inside the volume.

 

So to accomplish this, modify a shader, then update a material object, applied to a mesh object?

 

The gore in L4D2 is pretty extreme...

 

Haha, yes. It's an awesome game.

[Josh]

Okay, I think what they are doing, is they have wounds that are modeled on the character specially. This is a lot of work, and the wounds always end up looking the same, but it can work. Their problem was they didn't want the wounds to just sit on top of the character like a bad make-up job. They wanted the characters to actually have gaping holes. So they modeled the wound to go inside the character mesh, with a lip around the edge to meet the character mesh. But if they didn't do anything else, the wound would be inside the model, and you would not be able to see it.

 

So, they gave the shader an equation for the position of the wound mesh, and said "if the pixel occurs within this shape, discard it". This let them make those pixels invisible, which allows you to see through the character mesh and see the wound mesh they specially modeled.

 

So a special shader could handle the discard part, but it will take a lot of trial and error to get right.

[Rick]

I can't imagine actually having the job to do that stuff. That would be strange to tell your spouse what you did at work all day. That was a very interesting article though, thanks for sharing.

[Rekindled Phoenix]

I can't imagine actually having the job to do that stuff. That would be strange to tell your spouse what you did at work all day. That was a very interesting article though, thanks for sharing.

 

If you listen to the L4D2 developer commentary, there was a shared folder that was full of complete gore (purely for texturing models). After several artists loosing their lunch, they decided to use potato skins and other references that weren't made of people.