[Solved] Gdevelop is ignoring collision masks

I’ve followed the Gdevelop video tutorial for creating a collision mask. It seems very straightforward but the collision mask is ignored in the preview. Has anyone else had this problem?


Hello, Karmalution!

Can you share prints of your events so we can understand where is the difficulty? And if you can post prints of your colision box it helps too.

Do some basic checks

  • Platforms has the Platform behavior or in case you use physic is solid and unmovable
  • player has Platformer behavior

I agree with Rasterisko, we’ll need more info to assist:

Please show your events, your object behaviors, and your object collision masks.

Please also note: Platformer characters objects will only ever pay attention to the widest point and tallest point of a collision mask, in a box. It does not care about shapes on a platformer character mask.

Hi, thanks to you all for responding. Your questions were enough for me to figure out what I was getting wrong and the issue is now solved. All down to me being a newbie. Best wishes, Dave

Could you post what the mistake was? It may help other newbies if they face a similar issue.

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Of course. My embarrassingly obvious mistake was not realising that the collision mask was only for platform behaviours. I thought it was there for objects colliding, as well. Once I applied platform behaviours, it worked perfectly.

Thanks for everyone’s help.



Wait, I’m a bit confused. When I read karmalution’s solution I thought ‘really?’ I didn’t know collision masks were specific to platformer behaviour but happy to learn something new. But I just checked now and it works for top down movement. When the little blue creature collides with the block its tint changes. It hasn’t changed yet as the collision mask part isn’t touching the block. The block is just a block, no behaviours and the little blue creature isn’t a platformer object. So, collision masks can be used for objects colliding.


Collision masks are not specific to the platformer behavior.

The platformer behavior has very specific interactions with collision masks, in that platformer characters only pay attention to the widest point and tallest point, not any peaks/valleys.

Likewise, not all conditions care about collision masks. For example, the “Mouse/touch is on object” condition does not care about collision masks, ignoring any customization, and only pays attention to the full shape of the sprite asset (e.g. a square/rectangle/etc).

Similarly, other than sprite objects, you cannot directly modify the collision mask of any other object.

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