Hey there, I totally get the frustration when a seemingly straightforward condition just won’t fire—let’s walk through some common culprits here, based on how collision detection for complex shapes usually works:

• Double-check your collision condition logic
  The most likely issue is that your collision check in the draw method isn’t actually evaluating to true when you think it should. Let’s dig into potential gaps:

  • Are you comparing the right properties? For example, if you’re working with a UI framework like JavaFX (which Andrew Thompson often uses), make sure you’re using the correct coordinate bounds—getBoundsInLocal() vs getBoundsInParent() can throw off checks entirely.
  • Is there a coordinate system mismatch? If one shape uses scene coordinates and the other uses local coordinates, your collision check will never trigger.
  • Did you accidentally use a single = instead of == in your boolean condition? It’s a tiny typo but incredibly easy to miss!

• Verify your shape reference is correct
  If you’re targeting a specific square, make sure the variable you’re modifying is the exact same instance being checked for collision. Sometimes we accidentally create duplicate shapes or reference the wrong object, so the color change runs but affects an invisible or unrelated element.

• Add debug logs to trace the condition
  Stick a quick print statement right before your color change line to confirm what the collision check is returning. For example:

  System.out.println("Collision status: " + yourCollisionCondition);
  if (yourCollisionCondition) {
      square.setFill(Color.RED);
  }
  

  This will tell you definitively if the condition ever hits true—if it never prints true, you know the problem lies in the collision detection logic, not the color change line itself.

• Cross-reference Andrew Thompson’s original example line by line
  Go back to the Collision detection with complex shapes code and compare your draw method step by step:

  • Did you skip any key steps, like updating shape positions before running the collision check?
  • Are you using the same collision utility methods (like Shape.intersect()) that Andrew used? Custom collision logic often has edge cases you might not have accounted for.

• Check for timing or rendering order issues
  In many frameworks, the draw method runs on a loop. If your collision only occurs for a single frame, the red color might flash too fast to notice. Try setting a persistent flag when collision is detected, then keep the square red until the collision ends, instead of only changing it during the frame the collision happens.

Hopefully one of these points helps you track down the issue—collision detection bugs can be tricky, but breaking it down step by step usually reveals the problem!

内容的提问来源于stack exchange，提问作者totalthomas