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Routines |
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Used by the routine at DrawLevelObjects.
Draws each of the objects of a group of a cell, using DrawObject. The group is at IY and the cell is at CellPosition. The first byte of a group has the number of objects in bits 0-4, and if bit 4 of it is set there is an extra byte, as described for GroupTable. The next two bytes and the extra byte make up a row of flags that is shifted left by one bit after each object, so that each object has a flag of its own.
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| DrawGroupObjects | 47932 | LD HL,(23737) | Fetch the position of the cell. | |||||
| 47935 | LD A,L | Add the column of the cell to its row. | ||||||
| 47936 | ADD A,H | |||||||
| 47937 | LD (49062),A | Patch it into 49062 as the depth of the objects. | ||||||
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Work out where the view starts, relative to the cell, and patch it into the drawing code.
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| 47940 | LD HL,32768 | HL is 32768. | ||||||
| 47943 | LD DE,(23783) | Fetch the vertical origin of the view. | ||||||
| 47947 | AND A | Clear the carry flag. | ||||||
| 47948 | SBC HL,DE | Take the origin away. | ||||||
| 47950 | LD (49082),HL | Patch the result into 49082. | ||||||
| 47953 | LD HL,32831 | HL is 32831. | ||||||
| 47956 | LD DE,(23790) | Fetch the horizontal origin of the view. | ||||||
| 47960 | AND A | Clear the carry flag. | ||||||
| 47961 | SBC HL,DE | Take the origin away. | ||||||
| 47963 | LD (49249),HL | Patch the result into 49249. | ||||||
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Read the header of the group.
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| 47966 | PUSH IY | Put the address of the group onto the stack... | ||||||
| 47968 | POP IX | ...and take it off into IX. | ||||||
| 47970 | LD A,(IX+0) | Fetch the first byte of the group. | ||||||
| 47973 | AND %00011111 | Keep the number of objects. | ||||||
| 47975 | LD B,A | Keep it in B. | ||||||
| 47976 | LD H,(IX+1) | Fetch the first byte of the flags. | ||||||
| 47979 | LD L,(IX+2) | Fetch the second byte of the flags. | ||||||
| 47982 | INC IX | Move past the first byte of the group... | ||||||
| 47984 | INC IX | ...and the first byte of the flags. | ||||||
| 47986 | AND %00010000 | Test whether the group has an extra byte of flags. | ||||||
| DrawGroupObjects_Header | 47988 | JR Z,DrawGroupObjects_Objects | Jump to DrawGroupObjects_Objects if there is no extra byte, with A as zero. | |||||
| 47990 | LD A,(IX+1) | Fetch the extra byte of flags. | ||||||
| 47993 | INC IX | Move past the extra byte. | ||||||
| DrawGroupObjects_Objects | 47995 | LD (48014),HL | Patch the flags into the instructions that load them after each object... | |||||
| 47998 | LD (48012),A | ...including the extra byte. | ||||||
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Draw each object, and then move the row of flags along by one.
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| DrawGroupObjects_Loop | 48001 | INC IX | Move onto the first byte of the object. | |||||
| 48003 | PUSH BC | Save the number of objects left. | ||||||
| 48004 | CALL DrawObject | Draw the object. | ||||||
| 48007 | INC IX | Move past the second byte of the object... | ||||||
| 48009 | INC IX | ...and the third. | ||||||
| 48011 | LD A,0 | Fetch the extra byte of flags, which is patched in. | ||||||
| 48013 | LD HL,0 | Fetch the other two bytes of flags, which are patched in. | ||||||
| 48016 | RLA | Shift the extra byte left... | ||||||
| 48017 | RL L | ...then the second byte... | ||||||
| 48019 | RL H | ...and then the first byte. | ||||||
| 48021 | LD (48012),A | Patch the extra byte back in. | ||||||
| 48024 | LD (48014),HL | Patch the other two bytes back in. | ||||||
| 48027 | POP BC | Restore the number of objects left. | ||||||
| 48028 | DJNZ DrawGroupObjects_Loop | Decrease the number of objects and loop back to DrawGroupObjects_Loop until all of them have been drawn. | ||||||
| 48030 | RET | Return. | ||||||
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