Hi there!
Not knowing how the collision detection works in Space
Instigators, I thought to present mine. I once spent
almost a whole day for finding the optimal technique to
determine wether a particle hit a square and I think it
possibly might be adopted to detect a collision with
variable width invaders:
This is determining a wether a single pixel hit an 8*11
square:
LDA bulletHorPos,Y
ADC #$08
SBC horPosP0,X
BMI NoHit
SBC #$08
BPL NoHit
LDA verPosP0,X
SBC bulletVerPos,Y
BMI NoHit
SBC #$0B
BPL NoHit
I case the invader is only 6 pixel wide, it could still
be aligned on the left side of the sprite, so all that
was required to change in this code was adopting the
height from #$0B to the invader height and replacing the
hardcoded #$08 with a temporary variable.
Maybe that helps,
Greetings,
Manuel
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