The collision control register, CLXCON, contains the bits that define certain characteristics of collision detection. Its bits are shown in Table 7-4. Table 7-4: CLXCON Bits Bit Number Name Function ------ ---- -------- 15 ENSP7 Enable sprite 7 (OR with sprite 6) 14 ENSP5 Enable sprite 5 (OR with sprite 4) 13 ENSP3 Enable sprite 3 (OR with sprite 2) 12 ENSP1 Enable sprite 1 (OR with sprite 0) 11 ENBP6 Enable bitplane 6 (match required for collision) 10 ENBP5 Enable bitplane 5 (match required for collision) 9 ENBP4 Enable bitplane 4 (match required for collision) 8 ENBP3 Enable bitplane 3 (match required for collision) 7 ENBP2 Enable bitplane 2 (match required for collision) 6 ENBP1 Enable bitplane 1 (match required for collision) 5 MVBP6 Match value for bitplane 6 collision 4 MVBP5 Match value for bitplane 5 collision 3 MVBP4 Match value for bitplane 4 collision 2 MVBP3 Match value for bitplane 3 collision 1 MVBP2 Match value for bitplane 2 collision 0 MVBP1 Match value for bitplane 1 collision Bits 15-12 let you specify that collisions with a sprite pair are to include the odd-numbered sprite of a pair of sprites. The even-numbered sprites always are included in the collision detection. Bits 11-6 let you specify whether to include or exclude specific bitplanes from the collision detection. Bits 5-0 let you specify the polarity (true-false condition) of bits that will cause a collision. For example, you may wish to register collisions only when the object collides with "something green" or "something blue." This feature, along with the collision enable bits, allows you to specify the exact bits, and their polarity, for the collision to be registered. NOTE: ----- This register is write-only. If all bitplanes are excluded (disabled), then a bitplane collision will always be detected.
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