DirectX 2D Intersect

If you want it exactly a circle, the you can simply check the distance from the center. If that distance is larger than the radius, then it's too far away and must be moved back. (If you're a beginner I would start with this).
If you don't want it exactly a circle, but rather the exact pixel line as the edge, then it's more complicated. You must either keep the image in memory and compare the player position against those pixels, or create some kind of list of lines that define the edge.

Another option is to divide your map into smaller tiles, and mark every tile as open or closed, then do simple rectangle collision checks against those that are closed. This if often used in games.

do you think that you could write a small code example, I really dont know how to do it, sure a rectangle is easy, but a circle... i dunno

nu när jag ser att du dessutom är från sverige, kan du skriva på svenska? :)

I assume you have your player position, and have done a collision check against a rectangle. Modifying it to a circle is not very hard, you just instead of checking if 'character.x > maxX', check if 'distance to center > maxDist'.

point character;point center;// Check the distance from character to centerfloat xdistance = character.x - center.x;float ydistance = character.y - center.y;float distance = sqrt(xdistance*xdistance + ydistance*ydistance);if(distance > maxDistance) { // Move character back to the maximum distance from the center character.x = center.x + xdistance * maxDistance / distance; character.y = center.y + ydistance * maxDistance / distance;}