<49/54>VDP1 User's Manual/

★ HARDWARE Manual ★ VDP1 User's Manual ★ Chapter 7 Command

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VDP1 User's Manual/Chapter 7 Commands

■7.7 Polygon drawing commands

The polygon drawing commands draw rectangles into the frame buffer. Fills the inside of the rectangle with the specified color.
When the end bit is 0B and the command selection bit is 0100B, it is a polygon drawing command.
The contents of the command table are as follows:

bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 CMDCTRL +00 0 JP 0 0 0 0 0 0 Dir 0 1 0 0 CMDLINK +02 LINK specification/8H 0 0 CMDPMOD +04 M.O. 0 0 0 PC Cl Cm Me 1 1 0 0 0 color calculation CMDCOLR +06 non-textured color +08 +0A CMDXA +0C sign extension Vertex (A), X coordinate (XA) CMDYA +0E sign extension Vertex (A), Y coordinate (YA) CMDXB +10 sign extension Vertex (B), X coordinate (XB) CMDYB +12 sign extension Vertex (B), Y coordinate (YB) CMDXC +14 sign extension Vertex (C), X coordinate (XC) CMDYC +16 sign extension Vertex (C), Y coordinate (YC) CMDXD +18 sign extension Vertex (D), X coordinate (XD) CMDYD +1A sign extension Vertex (D), Y coordinate (YD) CMDGRDA +1C Gouraud shading table/8H 【note】 is ignored (don't care)

The polygon drawing command is defined as follows.

Setting the end bit to 0B and the command selection bit to 0100B makes it a polygon drawing command.

Specify the jump format. When the jump format is Assign or Call, divide the address of the next command table to be processed by 8H and set it to CMDLINK.

Set pre-clipping. Specify whether to enable or disable it, considering the clipping area and the drawing position of the part.

Specify the user clipping enable bit and clipping mode. Specifies whether user clipping is outside or inside in clipping mode.

Set mesh enable. Set MSB on for shade or window processing in VDP2.

Set the color mode to 000B. Set the color code to non-textured color (CMDCOLR) .

Specify color operation. Color calculation is valid when non-texture color is in RGB mode. If you do not want to perform color calculations, specify Replace. When performing Gouraud shading processing, divide the address of the Gouraud shading table by 8H and specify it. Gouraud shading processing is effective when the non-texture color is in RGB mode.

Set the upper left coordinates of the rectangle to be drawn as the vertex (A) (CMDXA, CMDYA), the upper right coordinates as the vertex (B) (CMDXB, CMDYB), the lower right coordinates as the vertex (C) (CMDXC, CMDYC), and the lower left coordinate as Define at vertex (D) (CMDXD, CMDYD). The positional relationship of the four vertices is arbitrary, so you can specify rotation and twist by specifying apex (A), apex (B), apex (C), and apex (D).

Note: If you set two vertices to the same coordinates, the polygon will be drawn as a triangle. If you set 4 vertices to the same coordinates, the polygon will be drawn with 1 pixel.

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★ HARDWARE Manual ★ VDP1 User's Manual ★ Chapter 7 Command