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Routines |
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Used by the routine at FlagOverlappingObjects.
Works out where an object is on the screen and how much of the screen its sprite covers. The width in bytes is one more than the width of the sprite if the sprite does not start on a byte boundary, because it has to be shifted across.
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Widen the sprite if it is shifted.
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| CalculateSpriteSize | 50749 | CALL CalculatePixelCoordinates | Call CalculatePixelCoordinates. | |||||
| 50752 | CALL GetSpriteAddress | Call GetSpriteAddress. | ||||||
| 50755 | LD A,(IX+26) | Fetch the pixel x position. | ||||||
| 50758 | AND %00000111 | Keep only bits 0-2. | ||||||
| 50760 | LD A,(DE) | Fetch the width of the sprite in bytes. | ||||||
| 50761 | INC DE | Move on to the height. | ||||||
| 50762 | JR Z,CalculateSpriteSize_Store | Jump to CalculateSpriteSize_Store if they were zero. | ||||||
| 50764 | INC A | Increment A. | ||||||
| CalculateSpriteSize_Store | 50765 | AND %00001111 | Keep only bits 0-3. | |||||
| 50767 | LD (IX+24),A | Store the width in bytes. | ||||||
| 50770 | LD A,(DE) | Fetch the height of the sprite in lines. | ||||||
| 50771 | LD (IX+25),A | Store the height in lines. | ||||||
| 50774 | RET | Return. | ||||||
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View the equivalent code in;
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