A map of warcraft textures

Recently I tried to import the World of Warcraft model and encountered many unexpected things. For example, if the vertex of. m2 is premultiplied by the bone offset matrix, I spent a lot of time searching for this matrix. As a result, it does not exist and is not required. Unexpectedly, it is used for one texture. It places other texture content in the fully transparent part of the texture. The principle is well understood. The four rgba channels are independent. When a is equal to 0, that is, completely transparent, the RGB value is meaningless; therefore, these RGB values can be used to store other values. You only need to ignore a and use them.

It is not difficult to support this situation in the engine, as long as the alpha channel can be selectively ignored. But after all, I just want to import its model, instead of fully supporting its functions. Do you want to support this trick? Why do you have to hesitate, because there are too many trick in professional games. To reduce memory overhead and improve performance, they often perform various technical operations on the art resources. These trick are often optimized at a specific hardware level and for a specific game, and are not universal. For example, one of the most common trick methods today is to combine the normal and highlight textures into one texture, which saves both memory and speed, but this method is not universal, if there are also self-luminous textures, different merging methods are required. Some of these trickProgramPre-processing generation, without the need for the artist to make it, some must be carefully considered by the artist.

The trick that stores other content in the transparent area must be considered by the artist. On the one hand, this requires a high level of experience for the artist, and on the other hand, it is contrary to the mainstream tools today. Not to mention Blizzard's art level. Most of the textures in the World of Warcraft model are single textures below 256x256, which is awesome. However, in order for such a small texture to provide sufficient details, each area of the texture is often applied to different areas of the model. The combination of transparent regions maximizes the texture utilization and effectively compresses the texture volume loaded at the same time. This means that the reuse of texture sub-areas must be taken into account in the modeling design. In case of modification and adjustment, the existing reuse scheme must be limited or re-initiated.

On the other hand, trick using alpha channels is increasingly difficult to use, because mainstream image tools such as PhotoShop no longer support importing and exporting independent Alpha channels. As mentioned above, when a is 0, the RGB value does not matter. In this case, you can select a special value for a Web image to increase the compression rate, in this case, the RGB values of pixels with a value of 0 are no longer the original values and cannot be used to store other information. Currently, only the superpng plug-in of the old version can import and export PNG with independent Alpha channels. The TGA has also been "optimized" in Photoshop 7.0, but since there have been numerous protests, the 7.01 version has resumed support for the Independent alpha channel, which is one reason why the game industry now uses the TGA format.