{ 3 obj.ryt=obj.mesh.rotation.y; 4 obj.rychange=parseFloat(obj.ryt - obj.ry0); 5 obj.ry0=obj.ryt; v0t = {forward: 0, left: 0, up: 0}; 8 v0t.forward = obj.v0.forward * parseFloat(Math.cos(obj.rychange)) + (-obj.v0.left * parseFloat(Math.sin(obj.rychange))); 9 v0t.left = (obj.v0.forward * parseFloat(Math.sin(obj.rychange))) + (obj.v0.left * parseFloat(Math.cos(obj.rychange))); 10 v0t.up = obj.v0.up; 11 obj.v0 = v0t;

　　物体在这一小段时间内可能绕y轴转过了一定角度，所以要把物体在上一时刻的自身坐标系速度投影到经过变化之后的自身坐标系中。

2、计算水平加速度，与水平位移

(obj.flag_standonground==1) { (obj.v0.forward == 0) { 6 obj.witha.forward = 0; 7 } (obj.v0.forward > 0) { 9 obj.witha.forward = -0.5; 10 } 11 else { 12 obj.witha.forward = 0.5; 13 } 14 if (obj.v0.left == 0) { 15 obj.witha.left = 0; 16 } (obj.v0.left > 0) { 18 obj.witha.left = -0.5; 19 } 20 else { 21 obj.witha.left = 0.5; 22 } obj.witha2.forward = obj.witha.forward+obj.witha0.forward; 25 obj.witha2.left = obj.witha.left+obj.witha0.left; (obj.keys.w != 0) { 29 obj.witha2.forward += 5; 30 } (obj.keys.s != 0) { 32 obj.witha2.forward -= 2; 33 } (obj.keys.a != 0 && obj.keys.d != 0) { } (obj.keys.a != 0) { 39 obj.witha2.left += 2; 40 } (obj.keys.d != 0) { 42 obj.witha2.left -= 2; 43 } 44 } { 47 obj.witha2.forward=0; 48 obj.witha2.left=0; 49 } (obj.witha2.forward!=0) 52 { ((0 < obj.vt.forward && obj.vt.forward < obj.vm.forward) || (0 > obj.vt.forward && obj.vt.forward > -obj.vm.backwards)) obj.mchange.forward = obj.witha2.forward * schange * schange + obj.v0.forward * schange; } (obj.vm.forward <= obj.vt.forward) {//超出最大速度则按最大速度算 59 obj.vt.forward = obj.vm.forward; 60 obj.mchange.forward = obj.vt.forward * schange; 61 } (-obj.vm.backwards >= obj.vt.forward) { 63 obj.vt.forward = -obj.vm.backwards; 64 obj.mchange.forward = obj.vt.forward * schange; 65 } 66 } 67 else {//无加速度时匀速运动 68 obj.mchange.forward = obj.v0.forward * schange; 69 } 70 if(obj.witha2.left!=0) 71 { ((0 < obj.vt.left && obj.vt.left < obj.vm.left) || (0 > obj.vt.left && obj.vt.left > -obj.vm.right)) obj.mchange.left = obj.witha2.left * schange * schange + obj.v0.left * schange; } (obj.vm.left <= obj.vt.left) { 78 obj.vt.left = obj.vm.left; 79 obj.mchange.left = obj.vt.left * schange; 80 } (-obj.vm.right >= obj.vt.left) { 82 obj.vt.left = -obj.vm.right; 83 obj.mchange.left = obj.vt.left * schange; 84 } 85 } 86 else { 87 obj.mchange.left = obj.v0.left * schange; 88 }

 3、计算垂直加速度、垂直位移：