HOW TO PVM EDIT SADX
Okay, first of all, what's a PVM file? A PVM file is the type of texture file that SADX uses. Each file may hold either one or two textures, or hundreds of textures. So I am going to teach you how to edit these.
First of all, make sure you have downloaded PVMedit, the software you will need for this. After you have downloaded this and saved it somewhere you will remember it, open it up. You should notice a button that says "File." Click it and go to open. Now, for this tutorial I am going to show you how to recolor Sonic, so go to the system folder of SADX and open a file called "SONIC.PVM." You should see a list of all of the textures that Sonic has. Here's a list of what they are:
mtx_kuchinaka0: I think it's some of Sonic's mouth.
mtx_kuchinaka0: Same as above.
s_anakage1: The opening in Sonic's gloves/socks.
s_hando2: The palm of Sonic's hands/gloves. This is also the texture for the white of his eyes.
s_hando3: Sonic's wrist/ankle.
s_testhand: Sonic's fingers.
stx_btest1: Sonic's main body/fur.
stx_eye2: The pupil and iris of sonic's eyes.
stx_ha: Sonic's teeth.
stx_hara: Sonic's stomach.
stx_hoho: Sonic's skin.
stx_itemring: Sonic's Crystal Ring powerup.
stx_itemshoos0: Sonic's light-speed shoes.
stx_kanagu: Sonic's shoe buckle (mask/alpha channel required).
stx_newspin: Sonic's jumping/spinning texture.
ym_sippse: Sonic's regular shoes.
Got that memorized? Good. Now, let me explain what the mask I told you about in the list is. A mask is used mostly for menus and two-dimensional textures. It says what the creator of the texture wants to show in the result and what not to show. In PVMedit you should see two buttons above the texture being displayed. One says "Image" and is highlighted. The other says "Mask." Now click on mask. You should see an all red texture. This means that all of the texture will show up. On three-dimensional textures, this doesn't matter, but on the buckle for Sonic's shoe, the mask is crucial. It is two-dimensional, so if the mask is all black, Sonic's shoes might fly off (not really, but you get what I mean, right?).
Okay, now find a texture you want to edit and right click on the image. Select "Export..." and save the picture where you will remember it. Now open any image editing program that supports bitmap files (which most do) and change the texture however you want. You can also search online for a texture and make it fit accordingly. Make sure the texture you make is the same size in pixels as the original.
Once you are done making your texture, go back to PVMedit and select the original texture. Right click on it and select "Import..." Select your new texture to put in. Now, if you are editing Sonic's shoe-strap, make sure you have a mask to go on it, or else it won't show up. In order to make a mask, draw white where you want to show up and black where you don't. Red sometimes works too, but I recommend white.
Now after putting in your texture, select your mask (or cancel to skip) and admire your texture. You can edit more, or finish with the one. Once done click on "File" and select "Save." You will be asked to make a backup file. Click yes and resave. Now startup SADX and enjoy!