sadx technobabble dump

stuff I didn't write:


guide to the model format


Stuff I did write:


I'm going to start posting more of my incomplete findings... mostly for completeness sake.


Earlier tonight I stumbled upon the loading cue, if you will, for special-use geometry in emerald coast. By special use, I mean sky boxes, death planes, water, etc. Anything where the code goes beyond simple "render this, read collision data". The problem with this is that I think its mostly program instructions and not variables, and even the tiniest alterations are crashing before I can even note their effect.


I also found three references to the skybox - which corresponds to the amount of times it is used (once per segment), they reside at:

Code:

keyed pointer value 17019504



Instances:

1011372

1011775

1012025

The loading function seems to process things in chunks (obviously), and interestingly enough it uses the byte 0x68 to determine where the end of one chunk is, and where the beginning of the next one is. However, it isn't consistent whatsoever, and editing things inside of the chunks isn't doing anything productive at all (even copy-pasting data from similar objects is causing the loader to crash) I think this is where geometry objects that are instanced (ie: more than one copy of exactly the same thing). Also, the examples I listed above are pretty simple, but still confusing the hell out of me. I know it works a little something like this:

Code:

chunk marker

pointer to seg struct

unknown (seems to be one byte and two shorts?)

chunk marker

Now I realize I'm probably the only person who gives a damn about this game, but I'm at a block here with the loading routine. If someone else could take a look into it, I'd be very appreciative.



Objects that don't fall under the special use category aren't listed here, but rather go under the collision structure (which is what I'm using for my level edits btw) How the game calculates collision (and also surface properties) is as follows:



start with 3 coordinates for an origin. Use the 4th float as a radius, and make a detection sphere using this data. The game constantly checks to see if sonic is inside this sphere, and if he is, it'll run the following surface properties. You can set basically any object to from non-solid to solid by making the flags read 01001080

Code:

Collision data

Unfinished





Struct Collision Data 0x24

Float X position; //

Float y position; //

Float z position; //

Float Spheresize; //

Float Unknown; //

Float padding; //

Dword Objectpointer; // points to OBJECT struct

Dword Unknown; // 

Short Unknown flags; // 01

Short Surface Flags; // These can hurt sonic, support sonic, take traction, etc



Unknown flags

0 - no collision

1 - default

2 - weird alpha



Surface flags (first byte)

type

1x = can land on

2x = push

3x = push

4x = Kill sonic

5x = no alpha, no col

6x = water

7x = lighting

8x = Stage Specific on/off (EC footprints)

9x = normal surf



behavior

x0 = normal

x1 = hurt

x2 = low traction

x3 = hurt



Surface Flags (second byte)

Visibility

1x = invisible (still solid)

8x = visible



Alpha blending

x0 = normal

x1 = blending mode 1

x2 = blending mode 2

Also, here's some tidbits on the player starts

Code:

=========================

Spawnpoints - better known as 'player starts', these define where in a map to start the player. Spawn point entries are always 0x14 bytes long

=========================



short x_rotation; // rotation values might not really be stored here, just a guess

short y_rotation; // 

short z_rotation; // 

short segue; // seems to affect how the spawn point is interpreted. Editing this can cause the player to start at 0,0,0

float x_position;

float y_position;

float z_position;

Code:

And Sonic's 'attack' state. This address jumps around, so I'm not going to list it until I find a pointer address.

00 - completely vulnerable, no jump ball.

05 - attack mode, can't be hurt by enemies, but not invulnerable. Jump ball will show if this is active

02 - light dash charged and holding, sonic will glow.

Code:

Material Struct -  keep bugging me to update this, so I'll actually do it

================================

Byte Blue_Diffuse; // This is the amount of blue light to add to the diffuse (texture) channel

Byte Green_Diffuse; // This is the amount of green light to add to the diffuse (texture) channel

Byte Red_Diffuse; // This is the amount of red light to add to the diffuse (texture) channel

Byte Alpha_Diffuse; // This is the transparency for the texture channel

Byte Blue_Specular; // This is the gloss or specularity, blue channel

Btye Green_Specular; // This is the specularity, red channel

Byte Red_specular; // This is the specularity, green chanel

Byte Alpha_specular; // This is the transparency for the specularity

Float unknown; // seems to act like a float most of the time

Byte TexID; // this is the pvr to load... not a gbix - I think the gbix is interpreted somewhere in the pvm caching function

Byte SomethingImportant; // crashes when put to FF

Byte unknown2[3]; //

Byte unknown3; // seems to be Ax (x being a variable)

Byte Spheremap; // first bit - U clamping, second bit - V clamping. Set to 21 to get normal uvs, set to 66 for screen mapping

Byte EndOfStruct; // always 94

edit: More structures added, fixed material struct it was horribly outdated, and STILL IS ARGH