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TrueSign, Member
Posted: 30 November 2012 08:16 PM Total Posts: 57
Hi,
I’m working on AwayPhysics for a first time. I was looking for any tutorials and there is not too much on the internet about that. I know that the newest version is based on bullet engine. I tried to find something there but without any results. My projects:
http://truesign.ie/projects/roulette/index.html
As you can see there, collision detection is now right. I played with these properties:
_physicsWorld.gravity = new Vector3D(0, -15, 0);
_physicsWorld.scaling = 80;
var sphereVector:Vector3D = new Vector3D(0, 60, 50);
_sphereShape = new AWPSphereShape(5);
sphereBody.position = sphereVector;
sphereBody.ccdSweptSphereRadius = 0.01;
sphereBody.ccdMotionThreshold = 0.01;
Few questions here:
1) When I set sphereBody.position to sphereVector my ball is moving constantly in that direction. I just want to set up starting position, not a movement direction. I saw there is no such a thing in examples. In examples when position is set up, ball stays in place.
2) on my projects ball is not moving down. It’s pushed away from the mesh. I played with ccdSweptSphereRadius and ccdMotionThreshold and _physicsWorld.scaling and sometimes ball it just stuck in the air, sometime it’s goes through meshes. What is the relation between that ccd’s properties? I was playing with that all day now, and still can’t find good solution.
3) I found that mesh sizes have influence on the whole engine. Is there a proper size for meshes to make this this work properly? My ball mesh is in 6 size, and on examples they use 100 size ball. I have tried to scale everything up but I couldn’t find correct set then.
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Yang Li, Administrator
Posted: 01 December 2012 03:03 AM Total Posts: 80
[ # 1 ]
How do you rotate the roulette wheel? should use applyTorque or set angularVelocity, Otherwise the ball will not collide with wheel.
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TrueSign, Member
Posted: 01 December 2012 12:59 PM Total Posts: 57
[ # 2 ]
Thanks Yang Li for your reply.
I use _board.rotationY += 1;
I have tried applyTorque and angularVelocity and roullete is not rotating. I found this thread: http://away3d.com/forum/viewthread/3218/ and I tried different techniques from there and only one working is:
var mtx:Matrix3D = boardBody.transform.clone();
mtx.prependRotation(1, Vector3D.Y_AXIS);
boardBody.transform = mtx;
Should I use applyTorque or angularVelocity in enterFrame? I have tried both ways. Maybe there is something wrong with me rigidBody setup:
_board = event.asset as Mesh;
_board.material = _boardMaterial;
_wholeScene.addChild(_board);
boardShape = new AWPBvhTriangleMeshShape(_board.geometry);
boardBody = new AWPRigidBody(boardShape, _board, 0);
_physicsWorld.addRigidBody(boardBody);
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Yang Li, Administrator
Posted: 01 December 2012 04:14 PM Total Posts: 80
[ # 3 ]
AWPBvhTriangleMeshShape is a static body, it can’t use applyTorque and angularVelocity, you should use a dynamic rigid body instead, for the wheel you can use the compound shape, and set its linearFactor = new Vector3d(0,0,0), set angularFactor = new Vector3d(0,1,0), to fix position and rotation, then set its angularVelocity to rotate around y axis.
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TrueSign, Member
Posted: 01 December 2012 04:20 PM Total Posts: 57
[ # 4 ]
I will test it. Thanks.
BTW: I found something wrong with my meshes. Or I think it’s wrong. I copied my assets to one of the awayPhysics examples and I found that:
http://truesign.ie/projects/physicsTest/
That green lines are very weird. So the problem here is my mesh? How can I solve that? (in attachment my shape - it’s not so complex)
Also, when I scale entire mesh up, that green line stays in a normal scale. Can I scale rigid body as well?
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TrueSign, Member
Posted: 01 December 2012 04:29 PM Total Posts: 57
[ # 5 ]
That compound shape should be build from available basic shapes right?
I can use cylinder for that centre part, and plane for that lower green part. But what can I use for that outer part? Inverted cylinder? Can I use something like that?
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Yang Li, Administrator
Posted: 02 December 2012 03:13 AM Total Posts: 80
[ # 6 ]
you are using a old version of awayphysics, you need update to lastest code: https://github.com/away3d/awayphysics-core-fp11/tree/dev
Here is another rigid body shape AWPGImpactMeshShape, it’s similar with AWPConvexHullShape but support concave. it have some bugs currently, but create roulette should be fine.
File Attachments
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TrueSign, Member
Posted: 03 December 2012 11:19 AM Total Posts: 57
[ # 7 ]
Thanks once again for help.
I haven’t used AWPGImpactMeshShape but I build up compound shape from many other basic shapes: cones, planes, boxes.
And it’s working! http://truesign.ie/projects/physicsTest/
However applyTorque or angularVelocity still doesn’t work. I have to use boardBody.transform = Matrix3D to rotate wheel.
Few more things I need to work out though. On my link I faked circular ball motion at the beginning with:
(in enterframe)
var rad:Number = angle * (Math.PI / 180);
_ball.x = radius * Math.cos(rad);
_ball.z = radius * Math.sin(rad);
angle += 4;
You can click on START btn to release ball from that movement. I used this:
var _x:Number = Math.round(_ball.x);
var _z:Number = Math.round(_ball.z);
var pos : Vector3D = new Vector3D(_x, 5, _z);
var rad:Number = (angle + 5) * (Math.PI / 180);
_x = Math.round(147 * Math.cos(rad));
_z = Math.round(147 * Math.sin(rad));
var mpos : Vector3D = new Vector3D(_x, 5, _z);
impulse = mpos.subtract(pos);
impulse.normalize();
impulse.scaleBy(10);
sphereBody.applyCentralImpulse(impulse);
Basically I’m checking for x and z position in angle + 5 to determine the impulse vector. But as you can see on my example it’s not working.
How I can use force or impulse to make ball moving around wheel?
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TrueSign, Member
Posted: 03 December 2012 11:51 AM Total Posts: 57
[ # 8 ]
Ok. Ball force fixed already. I had a plane that collides somehow with my ball.
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TrueSign, Member
Posted: 03 December 2012 04:26 PM Total Posts: 57
[ # 9 ]
One more thing before I finish. How to calculate angle in that moving objects ?
I pushed all numbers from wheel to an array. 37 number in total gives 9.73 angle for each number.
var ballAngle:Number = Math.round(Math.atan2(_ball.z, _ball.x) * (180 / Math.PI));
if (ballAngle < 0) {
ballAngle *= -1;
temp = 180 - ballAngle;
ballAngle = 180 + temp;
}
ballAngle -= 84; // shifted to match correct number
if (ballAngle < 0) {
ballAngle += 360;
}
var pickedNumber:uint = Math.round( ballAngle / 9.73);
trace("picked number: ",arrayNumbers[pickedNumber]);
and it’s working fine without wheel rotation. But board rotation is changing every frame and I have to subtract that angle from my ball angle and calculate that is out of my skills I think. I have tried many different methods and I end up here.
Maybe there is a much more simpler way to check on what number ball stays? Any ideas?
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Yang Li, Administrator
Posted: 04 December 2012 04:01 AM Total Posts: 80
[ # 10 ]
use dot product is simple, the code is
var v1:Vector3D = boardBody.right;
var v2:Vector3D = sphereBody.position.subtract(boardBody.position);
v2.normalize();
var angle:Number = Math.acos(v1.dotProduct(v2));
angle is radian between sphere and local x axis of boardBody.
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TrueSign, Member
Posted: 05 December 2012 11:11 AM Total Posts: 57
[ # 11 ]
Dot product seems like a good solution.
I have tried that and I found it’s working only partially.
I converted that angle to degrees like that:
var degrees:Number = Math.round(angle * 180 / Math.PI);
And degrees are from 0 to 180 only. I need 360 degrees in order to take correct number from my array.
You can see output here: http://truesign.ie/projects/physicsTest/
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TrueSign, Member
Posted: 05 December 2012 05:06 PM Total Posts: 57
[ # 12 ]
All right. I fixed it finally. Thanks for all your help.
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