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

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

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VDP1 User's Manual / Chapter 7 Commands

■ 7.8 Polyline drawing command

The polyline drawing command draws a rectangle in the framebuffer. The inside of the rectangle is not filled.
This is a polyline drawing command when the end bit is 0B and the command selection bit is 0101B.
The contents of the command table are as follows:

bit 15 14 13 12 11 Ten 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 designation / 8H 0 0 CMDPMOD +04 MO 0 0 0 Pc Cl Cm Me 1 1 0 0 0 Color calculation CMDCOLR +06 Non-texture 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 results in a polyline drawing command.
Specify the jump format. When the jump format is assign or call, divide the address of the command table to be processed next by 8H and set it to CMDLINK.
Set pre-clipping. Consider the clipping area and the drawing position of the part, and specify whether it is enabled or disabled.
Specifies the user clipping enabled bit and the clipping mode. Specifies whether user clipping is outside or inside in clipping mode.
Set mesh enable. When the mesh is enabled, the entire image may not be drawn depending on the position and shape of the polyline.
Sets the MSB on for shading or windowing in VDP2.
Set the color mode to 000B. Set the color code to non-texture color (CMDCOLR).
Specifies the color operation. Color calculation is effective when the non-texture color is in RGB mode. If you do not want to perform color calculation, specify replacement. When performing Gouraud shading processing, specify the address of the Gouraud shading table by dividing it by 8H. Gouraud shading is effective when the non-texture color is in RGB mode.
When translucent processing is performed with polylines, two lines overlap at each vertex, and as a result, translucency is applied twice, resulting in 3/4 of the original picture + 1/4 of the base.
When shadow processing is performed with poly lines, two lines overlap at each vertex, resulting in two shadows and half the brightness.
The upper left coordinate of the rectangle to be drawn is set to the vertex (A) (CMDXA, CMDYA), the upper right coordinate is set to the vertex (B) (CMDXB, CMDYB), the lower right coordinate is set to the vertex (C) (CMDXC, CMDYC), and the lower left coordinate is set. Define it on the vertex (D) (CMDXD, CMDYD). Since the positional relationship of the four vertices is arbitrary, you can specify rotation and twist by specifying vertices (A), vertices (B), vertices (C), and vertices (D).
Note: If you set the 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 in 1 pixel.

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