[英]Javascript Collision Detection between circle and polygon?
I'm unsure how to go about defining the area for a collision detection function when I have a polygon that looks like: 当我有一个看起来像这样的多边形时,我不确定如何去定义碰撞检测功能的区域:
______
/ _____|
/ /
/ /
---
I draw the polygon using lineTo() a few times before fill/stroke call so I know the x,y co-ords of all the points. 在填充/描边调用之前,我使用lineTo()绘制了多边形,所以我知道所有点的x,y坐标。
Currently I just check if the ball is beyond certain areas of points: 目前,我只检查球是否超出某些点区域:
if(tmpParticle.y <= platformBottom) {
if(tmpParticle.x < leftPipe_middleX || tmpParticle.x > rightPipe_middleX) {
tmpParticle = particleCollision(tmpParticle, platformBottom);
}
}
if(tmpParticle.y <= pipeBottom && tmpParticle.y >= pipeBottom - 30) {
if(tmpParticle.x < leftPipe_bottomRightX && tmpParticle.x > leftPipe_bottomLeftX) {
tmpParticle = particleCollision(tmpParticle, pipeBottom);
} else if (tmpParticle.x < rightPipe_bottomRightX && tmpParticle.x > rightPipe_bottomLeftX) {
tmpParticle = particleCollision(tmpParticle, pipeBottom);
}
}
platformHeight would be the Y value for the 'top horizontal line' platformBottom would be the Y value for the 'horizontal line just below platformHeight' rightPipe* is for the example shown. platformHeight将是“顶部水平线” platform的Y值,bottomHeight是“位于platformHeight下方水平线”的Y值,例如rightPipe *。 leftPipe* is for the same polygon except in the other direction (to form a pipe, where you must shoot the balls through without colliding).
leftPipe *用于同一多边形,但在另一个方向上除外(要形成管道,您必须在其中射出球而不会发生碰撞)。
My particleCollision() function just takes the tmpParticle and inverses the direction based on the Y value (2nd parameter, ie pipeBottom). 我的particleCollision()函数仅使用tmpParticle并根据Y值(第二个参数,即pipeBottom)反转方向。 This works fine for now though I may need to improve it later on.
尽管目前我可能需要稍后对其进行改进,但目前效果良好。
I just need to figure out a better way to define the area for collisions. 我只需要找出一种更好的方法来定义碰撞区域。
You may consider splitting your pipe into triangles and then finding triangle - circle
intersection area. 您可以考虑将管道分成三角形,然后找到
triangle - circle
相交区域。 If they do intersect the intersection will always be a convex polygon
(area is easy to calculate by splitting into triangles again) and a segment
(area is easy to calculate too - http://en.wikipedia.org/wiki/Circular_segment ). 如果它们相交,则相交将始终是
convex polygon
(易于通过再次拆分为三角形来计算面积)和segment
(也易于计算面积-http: //en.wikipedia.org/wiki/Circular_segment )。 The other case is the triangle itself, in case it lies inside the circle completely (a simple case again). 另一种情况是三角形本身,以防它完全位于圆内(再次是简单的情况)。
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