How do you reliably detect whether a sprite can move through an area of the map in a tile-based sidescroller or overhead view game? I''m designing a game with an engine like this, and I am occasionally able to move the edges of a sprite so that they overlap a solid tile, if I''m moving very quickly and in a diagonal direction. I''m currently using a somewhat "quick fix" method of detecting tile solidity. If a tile is detected near the sprite, it moves the sprite one pixel at a time, stopping as soon as a collision with a solid tile is detected, or the desired distance has been travelled in the x and y directions. I did it this way so that, no matter how thin a solid tile or platform is, or how fast a sprite is moving, it will never "jump" past a tile without detecting it. Unfortunately, since x and y corrdinates have to be incremented separately, there can be some errors when a sprite is moving very quickly and at an angle. My current plan is to have a special case for diagonal movement, with the y-increment being a ratio so that the function doesn''t assume a 45° angle. However, this seems somewhat convoluted and slow, so I suspect that there are many other alternatives out there. Any help would be greatly appreciated.

Thank You! This is a big help. I''ve put this method into my program, and now I can finally focus on other parts of it.

Thank You! This is a big help. I''ve put this method into my program, and now I can finally focus on other parts of it.