Quick answer: GameMaker collision_rectangle with prec = true skipping diagonal collisions? Precise checks use the mask’s bitmap, and rotated sprites need precise collision enabled on the sprite itself.
An enemy laser scan misses a target whose sprite extends into the rect’s corner. The target sprite isn’t marked Precise.
Enable Sprite-Side Precise
Open the target sprite → Collision Mask → Mode = Precise Per Frame. Without it, the engine uses the bounding box regardless of what you pass to the collision function.
Rotated Masks
For rotated sprites, precise masks rotate with the instance. Rectangle / circle masks don’t — pick precise if rotation matters for hit detection.
Performance Note
Precise per-frame masks are more expensive. Use Precise Per Bounding Box for static geometry; per-frame only when the silhouette changes drastically across animation frames.
Verifying
Diagonal-rotated targets register hits exactly where their pixels are visible.
“collision_rectangle’s prec flag only works if the sprite mask is precise too.”
For pixel-perfect platformers, precise masks plus subpixel position give you tight feel without the bounds-box fudge.