<50/54>VDP1 User's Manual/7.8 Polyline drawing command

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

▲ Back ｜ Forward ▼

VDP1 User's Manual/Chapter 7 Commands

■7.8 Polyline drawing command

The polyline drawing command draws a rectangle into the frame buffer. The inside of the rectangle is not filled.
When the end bit is 0B and the command selection bit is 0101B, it is a polyline 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 1 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 polyline drawing command is defined as follows.

Setting the end bit to 0B and the command selection bit to 0101B makes it a polyline 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. When mesh is enabled, the entire polyline may not be drawn depending on its position and shape.

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.

When applying translucency to a polyline, two lines overlap at each vertex, so the result is two degrees of translucency, resulting in 3/4 of the original painting + 1/4 of the base.

When performing shadow processing on a polyline, each vertex will have two lines overlapping, so the shadow will be cast twice and the brightness will be halved.

Set the upper left coordinate of the rectangle to be drawn as the vertex (A) (CMDXA, CMDYA), the upper right coordinate as the vertex (B) (CMDXB, CMDYB), the lower right coordinate 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 polyline will be drawn as a triangle. If you set 4 vertices to the same coordinates, the polyline will be drawn with 1 pixel.

▲ Back ｜ Forward ▼

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