4.Data structure

This chapter explains the structure of model data, material name specifications, and texture data handled by Sega Saturn.

4-1. Model data specifications

The model data here refers to a set of three data: point data of three-dimensional coordinates (x, y, x), polygon data formed by four of the points, and attribute data representing the attributes of the polygon. Masu.
Below is the general format when the model name is assumed to be "label".

point data

---

POINT point_label[]={   
      POStoFIXED(x,y,z),
      POStoFIXED(x,y,z),
      POStoFIXED(x,y,z),
      POStoFIXED(x,y,z),
           .............
      };                
	

POINT:Point data　
x,y,z:Float type coordinate values

This is the index of point data 0, 1, 2, 3 in order from the top.

polygon data

---

POLYGON polygon_label[]={
     NORMAL(x,y,z),      
     VERTICES(0,1,2,3),  
                         
     NORMAL(x,y,z),      
     VERTICES(0,1,2,3),  
          .............  
    };                   
	

NORMAL: Normal vector　
x,y,z:Float type coordinate values　
VERTICES: Point data of 4 points forming a polygon

For triangular polygons, repeat the last point to create 4 points of polygon data.

Example) For quadrilateral polygons

VERTICES(0,1,2,3)

Example) For triangular polygons

VERTICES(0,1,2,2)

attribute data

---

ATTR attribute_label=[]={                                           
        ATTRIBUTE(Plane,Sort,Texture,Color,Gouraud,Mode,Dir,Option),
         ....... .... ..... ... ... ..... ... .....          
                                                                    
        };                                                          
	

ATTR: Attribute　
Plane: Attribute to determine whether back side is present or not Sort: Representative point of Z sort　
Texture: Texture name (No.)　
Color: Color data　
Gouraud: Attribute of Gouraud shading Mode: Drawing mode　
Dir: State of polygons and textures Option: Options and other functions　

Attributes have the following eight parameters. Here we will describe the symbols that should actually be output for each parameter and their contents.

[Plane]

Single_Plane: Back side judgment available

Dual_Plane: No back side detection

[Sort]

SORT_MIN: Nearest point

SORT_CEN: center point

SORT_MAX: farthest point

SORT_BFR: Display in front of the polygon registered just before

[Texture]

No_Texture: For polygons

Texture name: For texture (macro indicating texture data)

For details, see “ Section 4-3 : Texture data specifications”.

[Color]

No_Palet: For textures

C_RGB( r, g, b: Color data for polygons
r, g, b represent the three primary colors, and each has a decimal value from 0 to 31.

[Gouraud]

No_Gouraud: No Gouraud

Address: relative address of Gouraud shading table

[Mode]

group	macro	Contents
[1]	No_Window	Not subject to restrictions within the window (default)
	Window_In	Display inside Window
	Window_Out	Display outside the window
[2]	MESHoff	Normal display (default)
	MESHon	Display as mesh
[3]	ECdis	Disable EndCode
	ECenb	Enable EndCode (default)
[4]	SPdis	Also display transparent pixels (default)
	SPenb	Do not display transparent pixels
[5]	CL16Bnk	16 colors Color bank mode (default)
	CL16Look	16 colors lookup table mode
	CL64Bnk	64 colors color bank mode
	CL128Bnk	128 colors color bank mode
	CL256Bnk	256 colors color bank mode
	CL32KRGB	32768 colors RGB mode
[6]	CL_Replace	Overwrite (standard) mode (default)
	CL_Shadow	shadow mode
	CL_Half	half brightness mode
	CL_Trans	Translucent mode
	CL_Gouraud	gouraud shading mode

[Dir]

macro	Contents
sprNoflip	Display texture normally
sprHflip	Flip the texture horizontally
sprVflip	Flip the texture vertically
sprHVflip	Flip the texture vertically and horizontally
sprPorygon	display polygons
sprPolyLine	display polyline
sprLine	Displays a straight line using the first two points

[Option]

macro	Contents
UseLight	Perform light source calculations
UseClip	Do not display if a vertex goes off the screen
Use Palette	Indicates that polygon colors are in palette format

Among the above parameters, Plane , Sort , and Mode can be obtained by specifying them in the material name in the next section.

PDATA structure

---

PDATA pdata_label[]={   
       point_label,n1,  
       polygon_label,n2,
       attribute_label  
      };                
	

pdata_label: Indicates the PDATA type address to be passed to SGL.
point_label: Indicates the address of the POINT type.　
nl: Indicates the number of points.　
polygon_label: Indicates the address of POLYGON type.　
n2: Indicates the number of polygons.　
attribute_label: Indicates the ATTR type address.　

---

OBJECT structure

---

OBJECT object_label[]={   
       pdata_label,       
       TRANSLATION(x,y,z),
       ROTATION(x,y,z),   
       SCALING(x,y,z),    
       object_child,      
       object_sibling,    

pdata_label: Indicates the PDATA type address.　
TRANSLATION: Indicates the amount of movement.　
ROTATION: Indicates the amount of rotation.　
SCALING: Indicates the amount of expansion.　
object_child: Indicates the address of the child's OBJECT type.
object_sibling: Indicates the address of the sibling OBJECT type.

Please refer to the “design 3” sample source for information on how to use this structure.

4-2. Material name specifications

Each character in the material name has a meaning. The contents will be reflected in the attribute data as is. Its specifications are shown below.

Generally, it is as follows.

[Plane][Sort][Mesh] ([] contains one character, and the material name is represented by three characters, for example “SSN”.)

The attributes of each character are

[Plane]

S:Single_Plane

D:Dual_Plane

[Sort]

N:SORT_MIN

C:SORT_CEN

F：SORT_MAX

B:SORT_BFR

[Mesh]

O：MESHon

N：MESHoff

Example) If the material name is “SCN”, the attribute data is

ATTRIBUTE( Single_Plane, SORT_CEN, No_Texture, C_RGB( r, g, b ), No_Gouraud, MESHoff, sprNoflip, NoOption )

It becomes.

4-3. Texture data specifications

This data is only required for textures. The texture name in the attribute data “Texture” is based on this data.

If the DGT file used as a texture is “sample.dgt”,

---

TEXDAT sample[]={                      
        rgb,rgb,rgb,rgb,rgb,rgb,rgb,rgb
        rgb,rgb,rgb,rgb,rgb,rgb,rgb,rgb
        ......................................  
        };                             

TEXTB: Texture table　
sample: Indicates a label with texture data (file name as is)
hsize,vsize: Texture size (hsize is always a multiple of 8)　
bgr: 1 pixel of texture data　

In addition, each of the three primary colors is expressed using 5 bits with a value between 0 and 31.
The data format is as follows.

	B					G					R
1	4	3	2	1	0	4	3	2	1	0	4	3	2	1	0

Example) Let's assume that the graphic data file sample.dgt is an 8x2 white and black checker texture as shown below.

Figure 4-1 Checkered texture

Then the texture data for this texture will be as follows.

---

TEXDAT sample[]={                                               
        0xffff,0x8000,0xffff,0x8000,0xffff,0x8000,0xffff,0x8000,
        0x8000,0xffff,0x8000,0xffff,0x8000,0xffff,0x8000,0xffff 
        };                                                      
	

---

The attribute data of the polygon with the material name “SCN” to which this texture is attached is as follows:

ATTRIBUTE(Single_Plane, SORT_CEN, SAMPLE, No_Palet, No_Gouraud, MESHoff, SprNoflip, NoOption)

It becomes.

Note

For textures, the H size must be a multiple of 8. This is a limitation due to Saturn's hardware specifications.