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optimised SAT._findSupports

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liabru 2021-05-01 15:56:35 +01:00
parent efede6e22d
commit 0d90a17f2d
1 changed files with 35 additions and 38 deletions
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69
src/collision/SAT.js
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@ -120,7 +120,7 @@ var Vector = require('../geometry/Vector');
collision.penetration.y = collision.normal.y * collision.depth;
// find support points, there is always either exactly one or two
var verticesB = SAT._findSupports(bodyA, bodyB, collision.normal),
var verticesB = SAT._findSupports(bodyA, bodyB, collision.normal, 1),
supports = [];
// find the supports from bodyB that are inside bodyA
@ -132,7 +132,7 @@ var Vector = require('../geometry/Vector');
// find the supports from bodyA that are inside bodyB
if (supports.length < 2) {
var verticesA = SAT._findSupports(bodyB, bodyA, Vector.neg(collision.normal));
var verticesA = SAT._findSupports(bodyB, bodyA, collision.normal, -1);
if (Vertices.contains(bodyB.vertices, verticesA[0]))
supports.push(verticesA[0]);
@ -219,52 +219,49 @@ var Vector = require('../geometry/Vector');
* Finds supporting vertices given two bodies along a given direction using hill-climbing.
* @method _findSupports
* @private
* @param {} bodyA
* @param {} bodyB
* @param {} normal
* @param {body} bodyA
* @param {body} bodyB
* @param {vector} normal
* @param {number} direction
* @return [vector]
*/
SAT._findSupports = function(bodyA, bodyB, normal) {
var nearestDistance = Number.MAX_VALUE,
vertexToBody = Vector._temp[0],
vertices = bodyB.vertices,
bodyAPosition = bodyA.position,
distance,
vertex,
SAT._findSupports = function(bodyA, bodyB, normal, direction) {
var vertices = bodyB.vertices,
verticesLength = vertices.length,
bodyAPositionX = bodyA.position.x,
bodyAPositionY = bodyA.position.y,
normalX = normal.x * direction,
normalY = normal.y * direction,
nearestDistance = Infinity,
vertexA,
vertexB;
vertexB,
vertexC,
distance,
j;
// find closest vertex on bodyB
for (var i = 0; i < vertices.length; i++) {
vertex = vertices[i];
vertexToBody.x = vertex.x - bodyAPosition.x;
vertexToBody.y = vertex.y - bodyAPosition.y;
distance = -Vector.dot(normal, vertexToBody);
// find deepest vertex relative to the axis
for (j = 0; j < verticesLength; j += 1) {
vertexB = vertices[j];
distance = normalX * (bodyAPositionX - vertexB.x) + normalY * (bodyAPositionY - vertexB.y);
// convex hill-climbing
if (distance < nearestDistance) {
nearestDistance = distance;
vertexA = vertex;
vertexA = vertexB;
}
}
// find next closest vertex using the two connected to it
var prevIndex = vertexA.index - 1 >= 0 ? vertexA.index - 1 : vertices.length - 1;
vertex = vertices[prevIndex];
vertexToBody.x = vertex.x - bodyAPosition.x;
vertexToBody.y = vertex.y - bodyAPosition.y;
nearestDistance = -Vector.dot(normal, vertexToBody);
vertexB = vertex;
var nextIndex = (vertexA.index + 1) % vertices.length;
vertex = vertices[nextIndex];
vertexToBody.x = vertex.x - bodyAPosition.x;
vertexToBody.y = vertex.y - bodyAPosition.y;
distance = -Vector.dot(normal, vertexToBody);
if (distance < nearestDistance) {
vertexB = vertex;
}
// measure next vertex
vertexC = vertices[(verticesLength + vertexA.index - 1) % verticesLength];
nearestDistance = normalX * (bodyAPositionX - vertexC.x) + normalY * (bodyAPositionY - vertexC.y);
// compare with previous vertex
vertexB = vertices[(vertexA.index + 1) % verticesLength];
if (normalX * (bodyAPositionX - vertexB.x) + normalY * (bodyAPositionY - vertexB.y) < nearestDistance) {
return [vertexA, vertexB];
}
return [vertexA, vertexC];
};
})();