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Added (incomplete) joints demo
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@josephg
josephg committed Jan 14, 2012
1 parent d7b1fe2 commit 2fcdb06
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7 changes: 7 additions & 0 deletions demo/Joints.html
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<canvas></canvas>
<script src="../cp.js"></script>
<script src="demo.js"></script>
<script src="Joints.js"></script>
<script>
(new Joints()).run();
</script>
239 changes: 239 additions & 0 deletions demo/Joints.js
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/* Copyright (c) 2007 Scott Lembcke
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/

var Joints = function() {
Demo.call(this);

var space = this.space;

var addBall = function(pos, boxOffset)
{
var radius = 15;
var mass = 1;
var body = space.addBody(new cp.Body(mass, cp.momentForCircle(mass, 0, radius, v(0,0))));
body.setPos(v.add(pos, boxOffset));

var shape = space.addShape(new cp.CircleShape(body, radius, v(0,0)));
shape.setElasticity(0);
shape.setFriction(0.7);

return body;
};

var addLever = function(pos, boxOffset)
{
var mass = 1;
var a = v(0, 15);
var b = v(0, -15);

var body = space.addBody(new cp.Body(mass, cp.momentForSegment(mass, a, b)));
body.setPos(v.add(pos, v.add(boxOffset, v(0, -15))));

var shape = space.addShape(new cp.SegmentShape(body, a, b, 5));
shape.setElasticity(0);
shape.setFriction(0.7);

return body;
};

var addBar = function(pos, boxOffset)
{
var mass = 2;
var a = v(0, 30);
var b = v(0, -30);

var body = space.addBody(new cp.Body(mass, cp.momentForSegment(mass, a, b)));
body.setPos(v.add(pos, boxOffset));

var shape = space.addShape(new cp.SegmentShape(body, a, b, 5));
shape.setElasticity(0);
shape.setFriction(0.7);

return body;
};

var addWheel = function(pos, boxOffset)
{
var radius = 15;
var mass = 1;
var body = space.addBody(new cp.Body(mass, cp.momentForCircle(mass, 0, radius, v(0,0))));
body.setPos(v.add(pos, boxOffset));

var shape = space.addShape(new cp.CircleShape(body, radius, v(0,0)));
shape.setElasticity(0);
shape.setFriction(0.7);
shape.group = 1; // use a group to keep the car parts from colliding

return body;
};

var addChassis = function(pos, boxOffset)
{
var mass = 5;
var width = 80;
var height = 30;

var body = space.addBody(new cp.Body(mass, cp.momentForBox(mass, width, height)));
body.setPos(v.add(pos, boxOffset));

var shape = space.addShape(new cp.BoxShape(body, width, height));
shape.setElasticity(0);
shape.setFriction(0.7);
shape.group = 1; // use a group to keep the car parts from colliding

return body;
};

space.iterations = 10;
space.gravity = v(0, -100);
space.sleepTimeThreshold = 0.5;

var staticBody = space.staticBody;
var shape;

for(var y = 480; y >= 0; y -= 120) {
shape = space.addShape(new cp.SegmentShape(staticBody, v(0,y), v(640,y), 0));
shape.setElasticity(1);
shape.setFriction(1);
shape.layers = NOT_GRABABLE_MASK;
}

for(var x = 0; x <= 640; x += 160) {
shape = space.addShape(new cp.SegmentShape(staticBody, v(x,0), v(x,480), 0));
shape.setElasticity(1);
shape.setFriction(1);
shape.layers = NOT_GRABABLE_MASK;
}

var boxOffset;
var body1, body2;

var posA = v( 50, 60);
var posB = v(110, 60);

var POS_A = function() { return v.add(boxOffset, posA); };
var POS_B = function() { return v.add(boxOffset, posB); };
//#define POS_A vadd(boxOffset, posA)
//#define POS_B vadd(boxOffset, posB)

// Pin Joints - Link shapes with a solid bar or pin.
// Keeps the anchor points the same distance apart from when the joint was created.
boxOffset = v(0, 0);
body1 = addBall(posA, boxOffset);
body2 = addBall(posB, boxOffset);
space.addConstraint(new cp.PinJoint(body1, body2, v(15,0), v(-15,0)));

// Slide Joints - Like pin joints but with a min/max distance.
// Can be used for a cheap approximation of a rope.
boxOffset = v(160, 0);
body1 = addBall(posA, boxOffset);
body2 = addBall(posB, boxOffset);
space.addConstraint(new cp.SlideJoint(body1, body2, v(15,0), v(-15,0), 20, 40));

// Pivot Joints - Holds the two anchor points together. Like a swivel.
boxOffset = v(320, 0);
body1 = addBall(posA, boxOffset);
body2 = addBall(posB, boxOffset);
body2.setAngle(Math.PI);
// cp.PivotJoint(a, b, v) takes it's anchor parameter in world coordinates. The anchors are calculated from that
// Alternately, specify two anchor points using cp.PivotJoint(a, b, anch1, anch2)
space.addConstraint(new cp.PivotJoint(body1, body2, v.add(boxOffset, v(80,60))));

// Groove Joints - Like a pivot joint, but one of the anchors is a line segment that the pivot can slide in
boxOffset = v(480, 0);
body1 = addBall(posA, boxOffset);
body2 = addBall(posB, boxOffset);
//space.addConstraint(cpGrooveJointNew(body1, body2, v(30,30), v(30,-30), v(-30,0)));

// Damped Springs
boxOffset = v(0, 120);
body1 = addBall(posA, boxOffset);
body2 = addBall(posB, boxOffset);
//space.addConstraint(cpDampedSpringNew(body1, body2, v(15,0), v(-15,0), 20, 5, 0.3f));

// Damped Rotary Springs
boxOffset = v(160, 120);
body1 = addBar(posA, boxOffset);
body2 = addBar(posB, boxOffset);
// Add some pin joints to hold the circles in place.
space.addConstraint(new cp.PivotJoint(body1, staticBody, POS_A()));
space.addConstraint(new cp.PivotJoint(body2, staticBody, POS_B()));
//space.addConstraint(cpDampedRotarySpringNew(body1, body2, 0, 3000, 60));

// Rotary Limit Joint
boxOffset = v(320, 120);
body1 = addLever(posA, boxOffset);
body2 = addLever(posB, boxOffset);
// Add some pin joints to hold the circles in place.
space.addConstraint(new cp.PivotJoint(body1, staticBody, POS_A()));
space.addConstraint(new cp.PivotJoint(body2, staticBody, POS_B()));
// Hold their rotation within 90 degrees of each other.
//space.addConstraint(cpRotaryLimitJointNew(body1, body2, -M_PI_2, M_PI_2));

// Ratchet Joint - A rotary ratchet, like a socket wrench
boxOffset = v(480, 120);
body1 = addLever(posA, boxOffset);
body2 = addLever(posB, boxOffset);
// Add some pin joints to hold the circles in place.
space.addConstraint(new cp.PivotJoint(body1, staticBody, POS_A()));
space.addConstraint(new cp.PivotJoint(body2, staticBody, POS_B()));
// Ratchet every 90 degrees
//space.addConstraint(cpRatchetJointNew(body1, body2, 0, M_PI_2));

// Gear Joint - Maintain a specific angular velocity ratio
boxOffset = v(0, 240);
body1 = addBar(posA, boxOffset);
body2 = addBar(posB, boxOffset);
// Add some pin joints to hold the circles in place.
space.addConstraint(new cp.PivotJoint(body1, staticBody, POS_A()));
space.addConstraint(new cp.PivotJoint(body2, staticBody, POS_B()));
// Force one to sping 2x as fast as the other
//space.addConstraint(cpGearJointNew(body1, body2, 0, 2));

// Simple Motor - Maintain a specific angular relative velocity
boxOffset = v(160, 240);
body1 = addBar(posA, boxOffset);
body2 = addBar(posB, boxOffset);
// Add some pin joints to hold the circles in place.
space.addConstraint(new cp.PivotJoint(body1, staticBody, POS_A()));
space.addConstraint(new cp.PivotJoint(body2, staticBody, POS_B()));
// Make them spin at 1/2 revolution per second in relation to each other.
//space.addConstraint(cpSimpleMotorNew(body1, body2, M_PI));

// Make a car with some nice soft suspension
boxOffset = v(320, 240);
var wheel1 = addWheel(posA, boxOffset);
var wheel2 = addWheel(posB, boxOffset);
var chassis = addChassis(v(80, 100), boxOffset);

//space.addConstraint(cpGrooveJointNew(chassis, wheel1, v(-30, -10), v(-30, -40), v(0,0)));
//space.addConstraint(cpGrooveJointNew(chassis, wheel2, v( 30, -10), v( 30, -40), v(0,0)));

//space.addConstraint(cpDampedSpringNew(chassis, wheel1, v(-30, 0), v(0,0), 50, 20, 10));
//space.addConstraint(cpDampedSpringNew(chassis, wheel2, v( 30, 0), v(0,0), 50, 20, 10));


};

Joints.prototype = Object.create(Demo.prototype);

addDemo('Joints', Joints);

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