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Routines |
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Used by the routine at HandlerPlayer.
Draws the car in the centre of the play area, using the frame from PlayerSpriteTable which matches the current direction.
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| DrawPlayer | 27193 | LD HL,(24080) | Fetch the direction the car is facing (Player_Direction). | |||||||
| 27196 | LD BC,32 | BC=0032 (half of a step between two of the 16 directions, so the direction is rounded to the nearest). | ||||||||
| 27199 | ADD HL,BC | HL=HL + BC. | ||||||||
| 27200 | LD A,H | A=H. | ||||||||
| 27201 | AND %00000011 | Keep only bits 0-1. | ||||||||
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Shift the top two bits of L into the bottom of A to make a direction between 0 and 15.
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| 27203 | RL L | Rotate L left and shift its top bit into A. | ||||||||
| 27205 | RLA | |||||||||
| 27206 | RL L | |||||||||
| 27208 | RLA | |||||||||
| 27209 | SLA A | Double A to use it as an index into a table of words. | ||||||||
| 27211 | LD HL,32548 | Point HL at the table of player sprites (PlayerSpriteTable). | ||||||||
| 27214 | LD C,A | Create an offset in BC. | ||||||||
| 27215 | LD B,0 | |||||||||
| 27217 | ADD HL,BC | HL=PlayerSpriteTable + offset. | ||||||||
| 27218 | LD E,(HL) | Fetch the pointer to the sprite of the player for this direction into DE. | ||||||||
| 27219 | INC HL | |||||||||
| 27220 | LD D,(HL) | |||||||||
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The player is drawn statically in the centre of the play area.
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| 27221 | LD HL,20371 | Set the screen address to draw the player at, the centre of the play area (20371). | ||||||||
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The player sprite is 2 bytes in width.
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| 27224 | LD A,2 | Write 2 to WidthCounter. | ||||||||
| 27226 | LD (24108),A | |||||||||
| 27229 | LD A,(DE) | Fetch the height of the sprite. | ||||||||
| 27230 | INC DE | Increment DE by one to point to the sprite data. | ||||||||
| 27231 | LD C,A | Keep the height of the sprite in C as the row counter. | ||||||||
| DrawPlayer_NextRow | 27232 | LD A,(24108) | Set the byte counter to the width of the sprite (WidthCounter). | |||||||
| 27235 | LD B,A | |||||||||
| 27236 | PUSH HL | Stash the screen address of the start of the row on the stack. | ||||||||
| DrawPlayer_NextCol | 27237 | LD A,(DE) | Copy a byte from DE (the player sprite data) to HL (the screen position). | |||||||
| 27238 | LD (HL),A | |||||||||
| 27239 | INC DE | Move on to the next byte of sprite data. | ||||||||
| 27240 | INC L | Move on to the next screen byte. | ||||||||
| 27241 | DJNZ DrawPlayer_NextCol | Decrease the byte counter by one and loop back to DrawPlayer_NextCol until the row has been drawn. | ||||||||
| 27243 | POP HL | Restore the screen address of the start of the row from the stack. | ||||||||
| 27244 | CALL ScreenPosition1PixelAbove | Call ScreenPosition1PixelAbove to move up one pixel line. | ||||||||
| 27247 | DEC C | Decrease the row counter by one and jump to DrawPlayer_NextRow until all of the rows have been drawn. | ||||||||
| 27248 | JR NZ,DrawPlayer_NextRow | |||||||||
| 27250 | RET | Return. | ||||||||
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