Thanks for the link. The documentation that comes with the install is really brief, hardly cover this topic. This is my take on their notation: Let's say that your precomputed normal map has three channels, RGB. A DXT5 has four channels for you to use, RGBA. A "xGBR" would be as follows R: x (nothing/black) G: G (you…
I don't know about Maya's 3Dc support... I haven't had the chance to use the format in production, I've just been interested in checking it out. It could be either that your card doesn't support it (unlikely these days) or that Maya's hardware shader doesn't (more likely). DXT5_nm written in your notation would be xRxBG I…
Hey guys, I was enlightened by one of my colleagues today on how DDS channel weighting works and we also discussed a few concepts on how to optimize this when it comes to normal maps. So far my test environment has been Maya 2011 (64-bit), a simple custom CGFX shader and Photoshop CS4 with the Nvidia DDS plugin. Also tried…
Cool powerpoint, worth a look. Now I understand BC7! Thanks for the image arrangemonk. BC7 is still the same old block compression like DXT, but each 4x4 block can use a different mode for allocating the precision, out of 8 modes. Pretty cool idea.
Ah, weird way to identify them. Do they have docs explaining exactly what each DXT5 method means? Doesn't make much sense just looking at it. Like, what would the difference be between xGBR and RBxG? For DXT, this page was helpful for me... http://msdn.microsoft.com/en-us/library/bb694531%28VS.85%29.aspx
Eric> Thanks :) Sorry if my text elements are confusing. I'm writing which channels i use of the RGBA space and which original input. So for example the DXT5_nm example i wrote "xGxR". I took the contents of the red channel and put it in the alpha channel. Then I blanked (black) the red and blue channel. I then saved this…
New comparison today. This time with a normal map which simulating a more realistic scenario. Yesterday was just a polygon plane trying to be a quite bulgy surface. It's arguable that a difference in shape of that caliber ought to justify altering the geometry of the low poly to match the shape better. This time I used The…
This looks pretty much right to me. The only one you aren't showing which is used a fair bit is half-res with uncompressed, which is pretty common. Recently at my job we started supporting DXT5 with xRBG (I think?) similar to what is described here ->…
I updated the pic in the original post. Included your suggestion cman2k. Works quite nice with this particular scenario. One thing that does not come through in my examples is that the half-res version would not have as crisp details if there were any? I mean my normal map in this case is mimicking a quite soft shape. A…