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// This file comes from Box2D-JS, Copyright (c) 2008 ANDO Yasushi.
// The original version is available at http://box2d-js.sourceforge.net/ under the
// zlib/libpng license (see License.txt).
// This version has been modified to make it work with O3D.
// NOTE: Changed this file pretty significantly. The original uses a
// canvas element and drew lines on it. This one just updates the positions and
// orientations of o3d objects to match the physics as well as using a
// scaled box to stand in for joints.
/**
* Draws all the object in the world.
* @param {Object} world A B2World object managing the physics world.
*/
function drawWorld(world) {
for (var j = world.m_jointList; j; j = j.m_next) {
drawJoint(j);
}
for (var b = world.m_bodyList; b; b = b.m_next) {
var o3dShape = b.GetUserData();
if (o3dShape) {
o3dShape.updateTransform(b);
}
}
}
/**
* Scales a joint transform to represnet a line.
* @param {Object} transformInfo An object with o3d information for the
* joint.
* @param {Object} p1 An object with x and y fields that specify the origin of
* the joint in 2d.
* @param {Object} p2 An object with x an dy fields that specify the far end of
* the joint in 2d.
*/
function scaleJointTransform(transformInfo, p1, p2) {
var dx = p2.x - p1.x;
var dy = p2.y - p1.y;
var length = Math.sqrt(dx * dx + dy * dy);
var transform = transformInfo.transform;
transform.identity();
transform.translate(p1.x, p1.y, 0);
transform.rotateZ(Math.atan2(-dx, dy));
transform.scale(2, length, 2);
}
/**
* Draws a joint
* @param {Object} joint A b2Joint object representing a joint.
*/
function drawJoint(joint) {
var transformInfo = joint.m_o3dTransformInfo;
if (!transformInfo) {
// This joint did not already have something in o3d to represent it
// so we create one here.
var transform = g.pack.createObject('Transform');
transform.parent = g.root;
transform.addShape(g.lineShape);
transformInfo = {
transform: transform
};
joint.m_o3dTransformInfo = transformInfo;
}
var b1 = joint.m_body1;
var b2 = joint.m_body2;
var x1 = b1.m_position;
var x2 = b2.m_position;
var p1 = joint.GetAnchor1();
var p2 = joint.GetAnchor2();
switch (joint.m_type) {
case b2Joint.e_distanceJoint:
scaleJointTransform(transformInfo, p1, p2);
break;
case b2Joint.e_pulleyJoint:
break;
default:
if (b1 == world.m_groundBody) {
scaleJointTransform(transformInfo, p1, x2);
}
else if (b2 == world.m_groundBody) {
scaleJointTransform(transformInfo, p1, x1);
}
else {
scaleJointTransform(transformInfo, x1, x2);
}
break;
}
}
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