View Full Version : Enhanced clip-maps

03-06-2003, 05:33 PM
Lightwave's clipmap feature could use a little attention... ;)

How about at least 8-bit clip maps, if not 24- or 32-bit support? Antialiased clip maps would be very handy, and considering that just about every game engine does this stuff in realtime, it's about time LW's clip maps got a boost.

Alternately, how about the ability to use a 2D vector graphic file (like an Adobe Illustrator document) as a clip map? This would be a workable alternative, as you would be able to sample the vectorgraphic at whatever resolution is necessary to get smooth curves along the edges of "clip-shapes" (and you'd still be able to work in 2-bit colourspace like LW's current clip maps do.)


03-06-2003, 11:52 PM
This is stupid. In the strict mathematical sense clip maps cannot be more than b/w images. They directly affect how your rays are fired through the scene (white = calculate intersection, black = ignore everything). What you are referring to is stencil buffer manipulation which is a totally different story. And its only so fast because it's done in hardware pixel shaders. However these are more like manipulating the alpha which we can already do with standard transparency mapping. What is annoying and where I have a problem is the fact that clip maps are the only way to get correctly shaped shadow maps on, lets say, leaves on a tree (mapped squares) and also the only way to remove all shading in areas where it is not needed (again, if you only use transparency mapping on leaves there can be odd results even though the same maps are used on specular etc.).

Having vector graphics support for texturing would indeed be very nice. I also have been thinking about this for a while and would love to see it. As I stated before this will not do anything to clip maps in the current implementation but could greatly benefit other things like hi-res logo stuff. Perhaps they will even include a special shader so we can have tiled vector elements with random placement and coloring etc..


03-07-2003, 02:13 AM

while you are basically right, using 8bit as opposed to 1bit does make a difference with clip maps.

Try this:
Create a clipmap in Photoshop, 8 bit (I dunno, type something, type is a good test). Save it as 8 bit .iff and 1 bit .iff.
Map it onto a plane as a clip map.
Zoom in really close to an edge.
Render with antialiasing.
See !
(I should actually try this again, last time I checked it made a difference in LW 5.6, lemme check...)

Both images are rendered with the same clip map size, and the same antialiasing options.

I just assume that you'd need a much higher 1 bit clipmap to get the edges as clean as the 1 bit version. With the 8 bit version LW can probably sample the image at a better quality when it comes to sub-pixel (in relation to the texture) clipping.

The 1 bit version:

03-07-2003, 02:14 AM
..and here is the 8 bit Version: