PRIMITIVE LIST'S MEMBER VARIABLES FORMAT


U_CHAR FLAG           - options for primitive
  {
  bit   0;            - LGT. Light source calculation
                        0 - On.   Light source calculation is carried out
                        1 - Off.  Light source calculation is not carried out
  bit   1;            - FCE. Determines if primitive is one or two faced
                        0 - Primitive has one face
                        1 - Primitive has two faces
  bit   2;            - GRD. Determines single or gradient pigment
                        0 - Primitive has one solid pigment
                        1 - Primitive has different pigments at each vertex
  bits  3-7;          - ignored
  }

Note
Most of these bits are set or cleared according to which type of primitive
is being created. Messing around with these may cause unexpected drawing or
crashes. The only bit you may want to edit manually is FCE.

U_CHAR MODE           - options for primitive
  {
  bit   0;            - TGE. Brightness calculation at time of calculation
                        0 - On.   Calculates light
                        1 - Off.  Draws texture as is (without lighting)
  bit   1;            - ABE. Activates translucency when rendered
                        0 - Off.  Primitive is rendered solid.
                        1 - On.   Primitive is rendered semitranslucent.
  bit   2;            - TME. Sets whether a texture is used or not
                        0 - Off.  No texture is rendered.
                        1 - On.   A texture is rendered.
  bit   3;            - displays whether a 3 or 4 sided polygon
                        0 - 3 sided polygon
                        1 - 4 sided polygon
  bit   4;            - IIP. Shading mode
                        0 - Flat shading
                        1 - Gouraud shading
  bits  5-7;          - Code. Defines which sort of entity to draw.
                        0 - Polygon (3 sided or 4 sided)
                        1 - Straight line
                        2 - Sprite
  }

Possible values of ABR (semitransparency method)
Note
Most of these bits are set or cleared according to which type of
primitive is being created. Messing around with these may cause
unexpected drawing or crashes. The only bit you may want to edit
manually is ABE.
For semitransparency to be used when the TMD is rendered, bit 30
of the GsDOBJ's attribute member must be set. To control the
semitransparency method, alter the ABR bits of the primitive's TSB
member (see below).

U_SHORT CBA           - position of CLUT in VRAM for primitives with textures
  {
  bits  0-5;          - upper 6 bits of 10 bits of X coordinate value
                        for CLUT in VRAM
  bits  6-14;         - 9 bits of Y coordinate value for CLUT in VRAM
  bit 15;             - ignored
  }

For example -
  u_long  CLUT_X_POS = 640;
  u_long  CLUT_Y_POS = 480;
  u_short CBA = (CLUT_X_POS >> 4) + (CLUT_Y_POS << 6);

U_SHORT TSB           - information about image for primitives with textures
  {
  bits  0-4;          - texture page number of texture
  bits  5-6;          - ABR. Semitransparency method (see below)
  bits  7-8;          - TPF. Colour mode of the texture (see below)
  bits  9-15;         - ignored
  }

Possible values of ABR (semitransparency method)
Note
For semitransparency to be used when the TMD is rendered, bit 30 of
the GsDOBJ's attribute member must be set, and the ABE bit of the
primitive's mode member must be set (see above).
  0     - 50% background  +50% polygon
  1     - 100% background +100% polygon
  2     - 100% background - 100% polygon
  3     - 100% background + 25% polygon
Possible values of TPF (colour mode)
  0     - 4 bit texture and CLUT
  1     - 8 bit texture and CLUT
  2     - 15 bit texture with no CLUT
For example -
  u_long  IMG_X_POS = 640;
  u_long  IMG_Y_POS = 0;
  u_long  ABR = 1;  // 100% back + 100% polygon
  u_long  TPF = 0;  // 16 colour texture
  u_short TXT_TPAGE;
  TXT_TPAGE = GetTPage((int) TPF, (int) ABR, IMG_X_POS, IMG_Y_POS);
  u_short TSB = (TXT_TPAGE) + (ABR << 5) + (TPF << 7);