Routines
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40863: Prepare Draw 2 Byte Sprite
Used by the routines at DrawEntity and DisplayEntity.
Does the same as PrepDraw23 for the sprite of the entity in IX (the new sprite). As well as the screen address, it records the width of the sprite in bytes in SpriteWidth, the number of rows to draw in New_Sprite_Row_Count and its height in SpriteHeight. The shifting routine at DrawActorSpriteRow_Aligned is set up for it.
Input
IX The entity
Output
C 0
DE The address of the first row of sprite data to draw
HL The screen address of the bottom row of the sprite
PrepDraw2 40863 CALL FetchActorSprite Fetch the address of the sprite of the entity with FetchActorSprite.
PrepDraw2_NoFetch 40866 LD L,(IX+3) L=the entity X position, and H=the entity Y position.
40869 LD H,(IX+4)
40872 LD A,L Fetch the X position.
40873 DEC A Decrease A by one.
40874 RLCA Multiply by 2.
40875 AND %00001110 Keep only bits 1-3.
40877 CP 14 Jump to PrepDraw2_Shift if this is not the maximum offset.
40879 JR NZ,PrepDraw2_Shift
40881 LD A,232 Use the offset which jumps to the code for sprites which are aligned to a character cell.
Self modifying code; this updates the operand of the JR command at 40746.
PrepDraw2_Shift 40883 LD (40746),A Write the offset to 40746.
A sprite which is aligned to a character cell is two bytes wide, otherwise it is three bytes wide.
40886 LD A,2 A=2.
40888 JR Z,PrepDraw2_Width Jump to PrepDraw2_Width if the offset was the maximum offset.
40890 INC A A=3.
PrepDraw2_Width 40891 LD (24080),A Write the width to SpriteWidth.
40894 CALL ScreenAddress Call ScreenAddress to get the screen address of the position.
40897 LD A,(DE) Fetch the number of rows in the sprite (the first byte of the sprite data).
40898 LD (24089),A Write the number of rows to New_Sprite_Row_Count.
40901 LD (24081),A Write the number of rows to SpriteHeight.
40904 JR PrepDraw23_Finish Jump to PrepDraw23_Finish to finish preparing the sprite.
View the equivalent code in;
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