Damping dependency of framerate

by **kallaspriit** » Tue Jul 14, 2009 6:21 am

My problem with linear and angular damping is that they are very dependent on simulation framerate as they are currently applied at same magnitude every frame so when you try to simulate at 300 FPS instead of 60, your objects will fly several times less and are much harder to rotate.

So my question is whether it is ok to set the damping every frame based on the timestep, for example in the force-torque callback. I am using OgreNewt and tried the following:

Code: Select all: void _CDECL Body::newtonForceTorqueCallback( const NewtonBody* body, float timeStep, int threadIndex ) { OgreNewt::Body* me = (OgreNewt::Body*)NewtonBodyGetUserData( body ); // 1 / 60 = 0.0166667 me->setLinearDamping(0.1f * (timeStep / 0.016667f)); me->setAngularDamping(Ogre::Vector3::UNIT_SCALE * 0.1f * (timeStep / 0.016667f)); if (me->m_forcecallback) me->m_forcecallback( me, timeStep, threadIndex ); }

This means that I am appliyng 0.1 damping at 60FPS and whenever the framerate is anything else, the damping coefficents are scaled as needed. I intend to take the 60FPS damping settings from my material system. It seems to work fine, my objects fly the same distance at 60 and 600 FPS but is there anything wrong with this approach, possibly performance penalty of setting it every frame?

Would you consider changing the damping system to something like:
void NewtonBodySetLinearDamping( const NewtonBody* bodyPtr, dFloat linearDamp, dFloat normalFPS = 60.0f)

So every time damping is applied, it is scaled by (timestep / (1/normalFPS)). This would make sure that damping is not framerate dependent and that seems to be the expected behaviour to me

by **JernejL** » Tue Jul 14, 2009 7:53 am

you could set the dampening to 0, and calculate it manually.

by **Julio Jerez** » Tue Jul 14, 2009 8:20 am

kallaspriit wrote:This means that I am appliyng 0.1 damping at 60FPS and whenever the framerate is anything else, the damping coefficents are scaled as needed. I intend to take the 60FPS damping settings from my material system. It seems to work fine, my objects fly the same distance at 60 and 600 FPS but is there anything wrong with this approach, possibly performance penalty of setting it every frame?

No nothing wrong with your method, I like it, Like delfi say you can take control of it yourself.
you are doin a tiem scale damping method,

It was my imporesion that Ogre people where running teh engien at a fix time step?
If thsi is so, then why is the Frame rate an issue them?

I must say that is is a about time people undernad that damping will away works that way.
the reason for this is that Damping is a non linear force.
It will try to see if I can do something aboout in the engine but like I it will never be unaffectd but simulation speed.

This is true for all numerial integration methods, even Gravity will act different when the simulation rate changes.

by **kallaspriit** » Tue Jul 14, 2009 8:45 am

Thank you for the explanation

I have another question about damping. In the real world, damping is mainly created by air drag and I wonder whether this could be modelled with NGD. I read up about the topic in wikipedia and found this could be done with quite a simple formula for which all the parameters but reference area are pretty much available in the engine already:

Would it be possible to project the collision mesh to a plane in the direction of body velocity and get the area of that shape? And how expensive would this be to do every frame or perhaps every n'th frame?

Not so good with the maths, perhaps someone has ideas

by **Julio Jerez** » Tue Jul 14, 2009 10:00 am

The damping in Newton has nothing to do with air drag, or any other kind of drag that might exist in the real world.
I added the Drag as default because in the early days of Newton, the engine was no very fast.
Many user were using the engine to do stupid demos where they shut balls and boxes with other balls, doing that add lots of bodies that never stopped moving.
so to made bodies to go to rest after some time by adding the default drag value to be 0.1

Newer versions I keep the values because of historical reasons.

by **kallaspriit** » Tue Jul 14, 2009 10:28 am

I understand that and I would like to stop using default damping system (damping = 0) and instead apply my own damping forces that are caused by air drag. The problem is calculating the area of an object on the plane of its heading direction, my math is not good enough. Can this be done real-time and how can this area be calculated?

by **JernejL** » Tue Jul 14, 2009 10:50 am

You could determine actual surface of the vehicle using either rough raycasting or calculating sillhuette of the object.

Since sillhuettes can now be calculated very fast in real time for use with stencil shadows there are plenty of algorythms to handle that, you can also cheat as optimization step, and calculate sillhuette only ever 2nd frame.

by **Julio Jerez** » Tue Jul 14, 2009 10:58 am

kallaspriit wrote:The problem is calculating the area of an object on the plane of its heading direction, my math is not good enough. Can this be done real-time and how can this area be calculated?

actuatly you could, I am no in the position to do it now because I am working on the toturials, But that funtionality is aready in Netwon 2.0

The is a helper object call Newton Mesh, you can can the body with a slicing plane an dget teh face of the cross section.
What you do is you make a NetwonMesh oput of teh collision shapes, and you use it to calculate teh cross section in the direction of the velocity bu slcing teh shape with a plane.
Basically the Drag value is calculated by using the area of the cross section of the shape mutiplied by a drag coeficient.
It is not so dificult to do that.

If you give me some time I can post the code for doing it in real time. But it can no be until I am finish with the tutorials.

by **kallaspriit** » Tue Jul 14, 2009 12:29 pm

That would be great, I'll be looking forward for this

by **JernejL** » Tue Jul 14, 2009 12:53 pm

kallaspiirit, you could also precalclate sillhuette in all perpendicular directions to model axis, and use that as base to detect how big area of a object is in any direction.

by **Julio Jerez** » Wed Jul 15, 2009 12:22 pm

KallaSring I was thonking about this last night and what Delfi say is right it is very eqssy to ge the area of teh shape perpendicula to teh travel velocity.

Basically it is the sum of all positive projection of the area of each face of the collision shape along teh diretion on teh velocity
here is a class to do it

Code: Select all: struct CalculateArea { dFloat area; dVector windDir; static void CalculateArea (void* userData, int vertexCount, const dFloat* faceVertec, int id) { int i; int value; dVector area (0.0f, 0.0f, 0.0f); dVector p0 (faceVertec[0 * 3 + 0], faceVertec[0 * 3 + 1], faceVertec[0 * 3 + 2]); dVector p1 (faceVertec[1 * 3 + 1], faceVertec[1 * 3 + 1], faceVertec[1 * 3 + 2]); dVector dp (p1 - p0); for (i = 2; i < vertexCount; i ++) { dVector p1 (faceVertec[i * 3 + 0], faceVertec[i * 3 + 1], faceVertec[i * 3 + 2]); dVector dp1 (p1 - p0); area += dp1 * dp0 dp0 = dp1; } CalculateArea* areaInfo = (CalculateArea*) userData; value = area % windDir; if (value > 0.0f) { areaInfo->area += value; } } CalculateArea (NewtonBody* body) { dFloat mag2; dMatrix matrix; NewtonBodyGetMatrix(body, &matrix[0][0]); NewtonBodyGetVelocity(body, &windDir[0]) mag2 = windDir % windDir; if (mag2 > 0.1f) { windDir *= 1.0f / dSqrt (mag2); NewtonCollisionForEachPolygonDo (NewtonBodyGetCollision(body), &matrix[0][0], CalculateArea, this); } } };

I did not test it but if you undertand the idea you can just make it compile and run.

by **kallaspriit** » Wed Jul 15, 2009 5:23 pm

Thank you, I will try this soon and let you know how it works out

by **kallaspriit** » Fri Jul 17, 2009 6:01 am

Tried this and can't seem to get it to work right. I do get values but these range from under one to hundreds and it seems to depend on the heading of the body. Perhaps I converted something wrong into OgreNewt world, but I have double-checked everything and cant find such conversion errors.

Here's debug output doing a circle with my car and the frame area being calculated:

Code: Select all: AREA: 2.11245e-37 AREA: 2.11245e-37 AREA: 2.11245e-37 AREA: 0.0911347 AREA: 0.0210342 AREA: 0.0210342 AREA: 0.195029 AREA: 0.217914 AREA: 0.217914 AREA: 0.197962 AREA: 0.175023 AREA: 0.175023 AREA: 0.152213 AREA: 0.152213 AREA: 0.129312 AREA: 0.106293 AREA: 0.106293 AREA: 0.0831742 AREA: 0.0831742 AREA: 0.0600224 AREA: 0.0600224 AREA: 0.0369266 AREA: 0.0185276 AREA: 0.0185276 AREA: 0.0165599 AREA: 0.0165599 AREA: 0.025931 AREA: 0.035114 AREA: 0.035114 AREA: 0.0442046 AREA: 0.0442046 AREA: 0.0532456 AREA: 0.0532456 AREA: 0.0585415 AREA: 0.215232 AREA: 0.215232 AREA: 0.201879 AREA: 0.201879 AREA: 0.184823 AREA: 0.170599 AREA: 0.170599 AREA: 0.0675618 AREA: 0.0675618 AREA: 0.0526527 AREA: 0.0393915 AREA: 0.0393915 AREA: 0.0438432 AREA: 0.0438432 AREA: 0.0455445 AREA: 0.0455445 AREA: 0.0492344 AREA: 0.0530007 AREA: 0.0530007 AREA: 0.0571082 AREA: 0.061359 AREA: 0.061359 AREA: 0.0656488 AREA: 0.0698068 AREA: 0.0698068 AREA: 0.0946672 AREA: 0.0540838 AREA: 0.0540838 AREA: 0.0561989 AREA: 0.0576009 AREA: 0.0576009 AREA: 0.0576457 AREA: 0.0576457 AREA: 0.0593497 AREA: 0.0598327 AREA: 0.0583557 AREA: 0.0583557 AREA: 0.0549437 AREA: 0.0549437 AREA: 0.0547653 AREA: 0.0489876 AREA: 0.0489876 AREA: 0.0433977 AREA: 0.0430733 AREA: 0.0430733 AREA: 0.0429689 AREA: 0.0507982 AREA: 0.0507982 AREA: 0.072832 AREA: 0.195625 AREA: 0.203276 AREA: 0.203276 AREA: 0.288566 AREA: 0.349005 AREA: 0.349005 AREA: 0.380043 AREA: 0.38172 AREA: 0.38172 AREA: 0.425389 AREA: 0.425389 AREA: 0.424075 AREA: 0.415536 AREA: 0.415536 AREA: 0.404667 AREA: 0.392521 AREA: 0.381622 AREA: 0.381622 AREA: 0.370509 AREA: 0.370509 AREA: 0.411706 AREA: 0.423846 AREA: 0.423846 AREA: 0.419494 AREA: 0.410885 AREA: 0.410885 AREA: 0.404377 AREA: 0.404377 AREA: 0.398048 AREA: 0.392537 AREA: 0.392537 AREA: 0.356207 AREA: 0.354757 AREA: 0.354757 AREA: 0.352282 AREA: 0.354186 AREA: 0.354186 AREA: 0.268301 AREA: 0.239054 AREA: 0.253517 AREA: 0.253517 AREA: 0.424053 AREA: 0.412751 AREA: 0.412751 AREA: 0.472497 AREA: 0.52526 AREA: 0.52526 AREA: 0.5701 AREA: 0.599337 AREA: 0.599337 AREA: 0.629766 AREA: 0.655642 AREA: 0.655642 AREA: 0.688989 AREA: 0.688989 AREA: 0.689353 AREA: 0.67835 AREA: 0.67835 AREA: 0.641792 AREA: 0.63328 AREA: 0.63328 AREA: 0.691257 AREA: 0.691257 AREA: 0.686218 AREA: 0.686218 AREA: 0.670486 AREA: 0.655995 AREA: 0.655995 AREA: 0.635419 AREA: 0.635419 AREA: 0.684473 AREA: 0.687273 AREA: 0.687273 AREA: 0.678913 AREA: 0.678913 AREA: 0.661535 AREA: 0.646071 AREA: 0.646071 AREA: 0.636546 AREA: 0.626189 AREA: 0.626189 AREA: 0.619422 AREA: 0.619422 AREA: 0.600594 AREA: 0.600594 AREA: 0.594911 AREA: 0.589374 AREA: 0.589374 AREA: 0.582461 AREA: 0.579816 AREA: 0.579816 AREA: 0.578373 AREA: 0.576241 AREA: 0.576241 AREA: 0.568238 AREA: 0.568238 AREA: 0.559498 AREA: 0.559498 AREA: 0.741759 AREA: 0.88661 AREA: 0.88661 AREA: 0.889548 AREA: 0.877517 AREA: 0.877517 AREA: 0.961303 AREA: 0.948028 AREA: 0.948028 AREA: 0.867415 AREA: 0.867415 AREA: 0.785284 AREA: 0.778478 AREA: 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AREA: 32.6087 AREA: 32.6087 AREA: 34.4354 AREA: 36.1643 AREA: 36.1643 AREA: 37.9003 AREA: 37.9003 AREA: 39.8592 AREA: 39.8592 AREA: 41.8767 AREA: 43.9407 AREA: 43.9407 AREA: 46.4073 AREA: 48.7781 AREA: 48.7781 AREA: 51.3612 AREA: 51.3612 AREA: 53.5506 AREA: 55.2265 AREA: 55.2265 AREA: 57.8229 AREA: 60.387 AREA: 60.387 AREA: 62.278 AREA: 63.9569 AREA: 63.9569 AREA: 65.9239 AREA: 67.6171 AREA: 67.6171 AREA: 69.9225 AREA: 71.776 AREA: 71.776 AREA: 73.9419 AREA: 75.9956 AREA: 75.9956 AREA: 75.9956 AREA: 77.9679 AREA: 79.813 AREA: 79.813 AREA: 82.0173 AREA: 83.7375 AREA: 83.7375 AREA: 85.243 AREA: 85.243 AREA: 86.6308 AREA: 88.8245 AREA: 88.8245 AREA: 90.4545 AREA: 92.1892 AREA: 92.1892 AREA: 93.9049 AREA: 93.9049 AREA: 95.4633 AREA: 97.3168 AREA: 97.3168 AREA: 98.9404 AREA: 98.9404 AREA: 100.468 AREA: 102.184 AREA: 102.184 AREA: 103.787 AREA: 103.787 AREA: 105.576 AREA: 106.814 AREA: 106.814 AREA: 107.978 AREA: 109.18 AREA: 109.18 AREA: 110.652 AREA: 111.96 AREA: 111.96 AREA: 113.19 AREA: 114.419 AREA: 114.419 AREA: 115.619 AREA: 116.787 AREA: 116.787 AREA: 117.914 AREA: 117.914 AREA: 118.923 AREA: 119.88 AREA: 119.88 AREA: 120.789 AREA: 120.789 AREA: 121.636 AREA: 122.49 AREA: 122.49 AREA: 123.304 AREA: 123.876 AREA: 123.876 AREA: 124.437 AREA: 124.991 AREA: 124.991 AREA: 125.53 AREA: 125.53 AREA: 126.152 AREA: 126.677 AREA: 126.677 AREA: 127.179 AREA: 127.179 AREA: 127.642 AREA: 128.068 AREA: 128.068 AREA: 128.498 AREA: 128.914 AREA: 128.914 AREA: 129.287 AREA: 129.287 AREA: 129.609 AREA: 129.85 AREA: 129.85 AREA: 130.102 AREA: 130.266 AREA: 130.266 AREA: 130.381 AREA: 130.534 AREA: 130.534 AREA: 130.584 AREA: 130.584 AREA: 130.646 AREA: 130.66 AREA: 130.66 AREA: 130.61 AREA: 130.61 AREA: 130.465 AREA: 130.555 AREA: 130.555 AREA: 130.365 AREA: 130.365 AREA: 130.214 AREA: 130.118 AREA: 130.118 AREA: 129.867 AREA: 129.638 AREA: 129.638 AREA: 129.458 AREA: 129.101 AREA: 129.101 AREA: 128.808 AREA: 128.808 AREA: 128.535 AREA: 128.075 AREA: 128.075 AREA: 127.641 AREA: 127.144 AREA: 127.144 AREA: 126.636 AREA: 126.103 AREA: 126.103 AREA: 125.551 AREA: 125.551 AREA: 124.947 AREA: 124.539 AREA: 124.539 AREA: 124.136 AREA: 124.136 AREA: 123.72 AREA: 123.322 AREA: 123.322 AREA: 123.023 AREA: 122.374 AREA: 122.374 AREA: 121.901 AREA: 121.259 AREA: 121.259 AREA: 120.516 AREA: 120.516 AREA: 119.861 AREA: 119.239 AREA: 119.239 AREA: 118.621 AREA: 118.621 AREA: 118.011 AREA: 118.011 AREA: 117.379 AREA: 116.731 AREA: 116.731 AREA: 116.072 AREA: 115.399 AREA: 115.399 AREA: 114.705 AREA: 114.705 AREA: 114.107 AREA: 113.542 AREA: 113.542 AREA: 112.985 AREA: 112.985 AREA: 112.418 AREA: 112.418 AREA: 111.841 AREA: 111.309 AREA: 111.309 AREA: 110.804 AREA: 110.804 AREA: 110.307 AREA: 109.796 AREA: 109.796 AREA: 109.256 AREA: 108.246 AREA: 107.739 AREA: 107.224 AREA: 107.224 AREA: 106.702 AREA: 106.173 AREA: 106.173 AREA: 105.639 AREA: 105.639 AREA: 105.111 AREA: 105.111 AREA: 104.614 AREA: 104.13 AREA: 104.13 AREA: 103.656 AREA: 103.656 AREA: 103.192 AREA: 102.736 AREA: 102.736 AREA: 102.288 AREA: 102.288 AREA: 101.847 AREA: 101.847 AREA: 101.414 AREA: 101.271 AREA: 101.271 AREA: 100.778 AREA: 100.778 AREA: 100.848 AREA: 100.354 AREA: 100.354 AREA: 100.017 AREA: 100.017 AREA: 100.083 AREA: 99.6171 AREA: 99.6171 AREA: 99.582 AREA: 99.1466 AREA: 99.1466 AREA: 98.8785 AREA: 98.8785 AREA: 98.5755 AREA: 98.2849 AREA: 98.2849 AREA: 97.98 AREA: 97.679 AREA: 97.679 AREA: 97.375 AREA: 97.0769 AREA: 97.0769 AREA: 96.7837 AREA: 96.7837 AREA: 96.4997 AREA: 96.225 AREA: 96.225 AREA: 95.9606 AREA: 95.9606 AREA: 95.9642 AREA: 95.697 AREA: 95.697 AREA: 95.5354 AREA: 95.5354 AREA: 95.7296 AREA: 95.2883 AREA: 95.2883 AREA: 95.1415 AREA: 94.9769 AREA: 94.9769 AREA: 94.8351 AREA: 94.8351 AREA: 94.693 AREA: 94.693 AREA: 94.567 AREA: 94.45 AREA: 94.45 AREA: 94.348 AREA: 94.348 AREA: 94.2593 AREA: 94.1863 AREA: 94.1863 AREA: 94.1276 AREA: 94.1276 AREA: 94.084 AREA: 94.0546 AREA: 94.0546 AREA: 94.2583 AREA: 94.2583 AREA: 94.2658 AREA: 94.3773 AREA: 94.3773 AREA: 94.8313 AREA: 94.8313 AREA: 94.6954 AREA: 94.8117 AREA: 94.8117 AREA: 94.9174 AREA: 94.9174 AREA: 95.0438 AREA: 95.1716 AREA: 95.1716 AREA: 95.3108 AREA: 95.3108 AREA: 95.4548 AREA: 95.6085 AREA: 95.6085 AREA: 95.7685 AREA: 95.7685 AREA: 95.9374 AREA: 96.1153 AREA: 96.1153 AREA: 96.3043 AREA: 96.3043 AREA: 96.7015 AREA: 96.7015 AREA: 96.9311 AREA: 97.2421 AREA: 97.2421 AREA: 97.8134 AREA: 97.9798 AREA: 97.9798 AREA: 98.3032 AREA: 98.3032 AREA: 98.6142 AREA: 98.9389 AREA: 98.9389 AREA: 99.2595 AREA: 99.2595 AREA: 99.5856 AREA: 99.9126 AREA: 99.9126 AREA: 100.247 AREA: 100.247 AREA: 100.588 AREA: 100.936 AREA: 100.936 AREA: 101.466 AREA: 101.466 AREA: 101.853 AREA: 101.853 AREA: 102.325 AREA: 103.047 AREA: 103.047 AREA: 103.332 AREA: 103.332 AREA: 103.774 AREA: 104.202 AREA: 104.202 AREA: 104.636 AREA: 104.636 AREA: 105.062 AREA: 105.49 AREA: 105.49 AREA: 105.914 AREA: 106.34 AREA: 106.34 AREA: 106.764 AREA: 106.764 AREA: 107.19 AREA: 107.19 AREA: 107.772 AREA: 108.22 AREA: 108.22 AREA: 108.727 AREA: 108.727 AREA: 109.49 AREA: 109.49 AREA: 109.827 AREA: 110.289 AREA: 110.289 AREA: 110.742 AREA: 111.196 AREA: 111.196 AREA: 111.635 AREA: 111.635 AREA: 112.07 AREA: 112.07 AREA: 112.495 AREA: 112.914 AREA: 112.914 AREA: 113.48 AREA: 113.48 AREA: 113.902 AREA: 113.902 AREA: 114.393 AREA: 115.17 AREA: 115.17 AREA: 115.485 AREA: 115.485 AREA: 115.881 AREA: 115.881 AREA: 116.205 AREA: 116.205 AREA: 116.565 AREA: 116.9 AREA: 116.9 AREA: 117.404 AREA: 117.751 AREA: 117.751 AREA: 118.192 AREA: 118.192 AREA: 118.895 AREA: 118.895 AREA: 119.195 AREA: 119.522 AREA: 119.522 AREA: 120.073 AREA: 120.073 AREA: 120.472 AREA: 121.095 AREA: 121.095 AREA: 121.35 AREA: 121.35 AREA: 121.701 AREA: 122.009 AREA: 122.009 AREA: 122.401 AREA: 122.401 AREA: 122.677 AREA: 123.029 AREA: 123.029 AREA: 123.542 AREA: 123.542 AREA: 123.735 AREA: 123.735 AREA: 123.959 AREA: 124.358 AREA: 124.358 AREA: 124.499 AREA: 124.499 AREA: 124.717 AREA: 125.102 AREA: 125.102 AREA: 125.166 AREA: 125.166 AREA: 125.318 AREA: 125.318 AREA: 125.452 AREA: 125.761 AREA: 125.761 AREA: 125.582 AREA: 125.582 AREA: 125.507 AREA: 125.46 AREA: 125.46 AREA: 125.57 AREA: 125.57 AREA: 125.162 AREA: 125.162 AREA: 124.912 AREA: 124.594 AREA: 124.594 AREA: 124.594 AREA: 124.186 AREA: 123.749 AREA: 123.749 AREA: 123.342 AREA: 123.342 AREA: 122.793 AREA: 122.29 AREA: 122.29 AREA: 121.976 AREA: 121.976 AREA: 121.265 AREA: 121.265 AREA: 120.77 AREA: 120.039 AREA: 120.039 AREA: 119.197 AREA: 119.197 AREA: 118.39 AREA: 118.39 AREA: 117.738 AREA: 116.59 AREA: 116.59 AREA: 115.56 AREA: 115.56 AREA: 114.479 AREA: 114.479 AREA: 113.534 AREA: 113.534 AREA: 112.106 AREA: 110.748 AREA: 110.748 AREA: 109.403 AREA: 109.403 AREA: 108.269 AREA: 108.269 AREA: 106.412 AREA: 106.412 AREA: 104.876 AREA: 103.14 AREA: 103.14 AREA: 101.425 AREA: 101.425 AREA: 99.9371 AREA: 99.9371 AREA: 97.9663 AREA: 97.9663 AREA: 96.2511 AREA: 94.2146 AREA: 94.2146 AREA: 92.0618 AREA: 92.0618 AREA: 89.911 AREA: 89.911 AREA: 87.9956 AREA: 87.9956 AREA: 85.4453 AREA: 85.4453 AREA: 82.9912 AREA: 80.534 AREA: 80.534 AREA: 78.3767 AREA: 78.3767 AREA: 75.3603 AREA: 75.3603 AREA: 72.6833 AREA: 72.6833 AREA: 69.8614 AREA: 69.8614 AREA: 67.0622 AREA: 67.0622 AREA: 64.6204 AREA: 64.6204 AREA: 61.5756 AREA: 61.5756 AREA: 58.8284 AREA: 55.9687 AREA: 55.9687 AREA: 53.2339 AREA: 53.2339 AREA: 50.5278 AREA: 50.5278 AREA: 48.1511 AREA: 48.1511 AREA: 45.0426 AREA: 45.0426 AREA: 42.13 AREA: 39.5717 AREA: 39.5717 AREA: 36.5365 AREA: 36.5365 AREA: 33.5741 AREA: 33.5741 AREA: 31.0295 AREA: 27.8956 AREA: 27.8956 AREA: 27.8956 AREA: 24.9444 AREA: 21.9943 AREA: 21.9943 AREA: 19.438 AREA: 19.438 AREA: 16.6087 AREA: 16.6087 AREA: 14.527 AREA: 12.4962 AREA: 12.4962 AREA: 10.8377 AREA: 10.8377 AREA: 9.90262 AREA: 9.08192 AREA: 9.08192 AREA: 8.22022 AREA: 7.69829 AREA: 7.69829 AREA: 7.08267 AREA: 7.08267 AREA: 6.47859 AREA: 6.47859 AREA: 5.90623 AREA: 5.90623 AREA: 5.42328 AREA: 5.42328 AREA: 4.8144 AREA: 4.33803 AREA: 4.33803 AREA: 3.74034 AREA: 3.74034 AREA: 3.15838 AREA: 3.15838 AREA: 3.13649 AREA: 3.13649 AREA: 3.27461 AREA: 3.36814 AREA: 3.36814 AREA: 3.50491 AREA: 3.50491 AREA: 3.60449 AREA: 3.60449 AREA: 3.7008 AREA: 3.80052 AREA: 3.80052 AREA: 3.92773 AREA: 3.92773 AREA: 4.0114 AREA: 4.0114 AREA: 4.11262 AREA: 4.18042 AREA: 4.18042 AREA: 4.24566 AREA: 4.24566 AREA: 4.31237 AREA: 4.31237 AREA: 4.4053 AREA: 4.45244 AREA: 4.45244 AREA: 4.5179 AREA: 4.5179 AREA: 4.55577 AREA: 4.61467 AREA: 4.61467 AREA: 4.60288 AREA: 4.60288 AREA: 4.62744 AREA: 4.64029 AREA: 4.64029 AREA: 4.65143 AREA: 4.65143 AREA: 4.68356 AREA: 4.6771 AREA: 4.6771 AREA: 4.6811 AREA: 4.6811 AREA: 4.66713 AREA: 4.66713 AREA: 4.6659 AREA: 4.6659 AREA: 4.61397 AREA: 4.61397 AREA: 4.58027 AREA: 4.58027 AREA: 4.54352 AREA: 4.52484 AREA: 4.52484 AREA: 4.47438 AREA: 4.43815 AREA: 4.43815 AREA: 4.35725 AREA: 4.28532 AREA: 4.28532 AREA: 4.28532 AREA: 4.21993 AREA: 4.16782 AREA: 4.16782 AREA: 4.08104 AREA: 4.08104 AREA: 4.00677 AREA: 3.91394 AREA: 3.91394 AREA: 3.82812 AREA: 3.82812 AREA: 3.68995 AREA: 3.68995 AREA: 3.56293 AREA: 3.56293 AREA: 3.44059 AREA: 3.44059 AREA: 3.34415 AREA: 3.34415 AREA: 3.21715 AREA: 3.08762 AREA: 3.08762 AREA: 2.95926 AREA: 2.82452 AREA: 2.82452 AREA: 2.70202 AREA: 2.70202 AREA: 2.55314 AREA: 2.39526 AREA: 2.39526 AREA: 2.2434 AREA: 2.2434 AREA: 2.08501 AREA: 2.08501 AREA: 1.93359 AREA: 1.93359 AREA: 1.80115 AREA: 1.80115 AREA: 1.67003 AREA: 1.5422 AREA: 1.5422 AREA: 1.40137 AREA: 1.40137 AREA: 1.26286 AREA: 1.12594 AREA: 1.12594 AREA: 0.978692 AREA: 0.833399 AREA: 0.833399 AREA: 0.77069 AREA: 0.77069 AREA: 0.704085 AREA: 0.704085 AREA: 0.64399 AREA: 0.64399 AREA: 0.580173 AREA: 0.720693 AREA: 0.720693 AREA: 0.839543 AREA: 0.839543 AREA: 0.980654 AREA: 1.10173 AREA: 1.10173 AREA: 1.30825 AREA: 1.30825 AREA: 1.54798 AREA: 1.54798 AREA: 1.79265 AREA: 2.01562 AREA: 2.01562 AREA: 2.24544 AREA: 2.24544 AREA: 2.37697 AREA: 2.5354 AREA: 2.5354 AREA: 2.64555 AREA: 2.64555 AREA: 2.78511 AREA: 2.87647 AREA: 2.87647 AREA: 3.00708 AREA: 3.07881 AREA: 3.07881 AREA: 3.18913 AREA: 3.33307 AREA: 3.33307 AREA: 3.5109 AREA: 3.5109 AREA: 3.58905 AREA: 3.69771 AREA: 3.73149 AREA: 3.73149 AREA: 3.81481 AREA: 3.81481 AREA: 3.8295 AREA: 3.8295 AREA: 3.91404 AREA: 3.92872 AREA: 3.92872 AREA: 4.01126 AREA: 4.0561 AREA: 4.0561 AREA: 4.39899 AREA: 4.39899 AREA: 4.57778 AREA: 4.57778 AREA: 5.11293 AREA: 5.34812 AREA: 5.34812 AREA: 5.85807 AREA: 5.8115 AREA: 5.8115 AREA: 6.47241 AREA: 6.47241 AREA: 7.09279 AREA: 7.64316 AREA: 7.64316 AREA: 8.02736 AREA: 8.02736 AREA: 8.28481 AREA: 7.91995 AREA: 7.91995 AREA: 8.54979 AREA: 8.54979 AREA: 8.87489 AREA: 8.86475 AREA: 8.86475 AREA: 9.28726 AREA: 9.18412 AREA: 9.18412 AREA: 9.49694 AREA: 9.49694 AREA: 9.34223 AREA: 9.56848 AREA: 9.56848 AREA: 10.0714 AREA: 10.0714 AREA: 10.9258 ! Body 'Ball_0' l AREA: 10.7776 AREA: 10.7776 AREA: 11.3537 AREA: 11.1799 AREA: 11.3288 AREA: 11.3288 AREA: 11.0954 AREA: 10.7287 AREA: 10.7287 AREA: 10.0188 AREA: 10.0188 AREA: 10.185 AREA: 9.68774 AREA: 9.69189 AREA: 9.69189 AREA: 8.84918 AREA: 8.99271 AREA: 8.99271 AREA: 8.40923 AREA: 8.40923 AREA: 8.4468 AREA: 8.4468 AREA: 7.56661 AREA: 7.75404 AREA: 7.75404 AREA: 6.98716 AREA: 6.98716 AREA: 6.98935 AREA: 5.9361 AREA: 5.9361 AREA: 5.96992 AREA: 5.04033 AREA: 5.04033 AREA: 4.8471 AREA: 3.66138 AREA: 3.66138 AREA: 3.50574 AREA: 3.50574 AREA: 2.33141 AREA: 1.99944 AREA: 1.99944 AREA: 1.07315 AREA: 0.946074 AREA: 0.350568 AREA: 0.350568 AREA: 0.273199 AREA: 0.0455135 AREA: 0.0455135 AREA: 0.0515759 AREA: 0.0515759 AREA: 0.0437208 AREA: 0.0496671 AREA: 0.0496671 AREA: 0.0405396 AREA: 0.0405396 AREA: 0.0551322 AREA: 0.0434205 AREA: 0.0434205 AREA: 0.0502397 AREA: 0.040211 AREA: 0.040211 AREA: 0.047699 AREA: 0.047699 AREA: 0.035197 AREA: 0.0422589 AREA: 0.0422589 AREA: 0.0321678 AREA: 0.0393137 AREA: 0.0393137 AREA: 0.029473 AREA: 0.029473 AREA: 0.0328831 AREA: 0.0267131 AREA: 0.0267131 AREA: 0.0275262 AREA: 0.023803 AREA: 0.022607 AREA: 0.022607 AREA: 0.0205625 AREA: 0.0191315 AREA: 0.0191315 AREA: 0.0170849 AREA: 0.0153579 AREA: 0.0153579 AREA: 0.013335 AREA: 0.0120254 AREA: 0.0120254 AREA: 0.0109171 AREA: 0.00986852 AREA: 0.00986852 AREA: 0.00877321 AREA: 0.00754966 AREA: 0.00754966 AREA: 0.00651992 AREA: 0.00651992 AREA: 0.00519344 AREA: 0.00422495 AREA: 2.11245e-37 AREA: 2.11245e-37

Here is my code:

Code: Select all: #ifndef MESHAREACALCULATOR_H_INCLUDED #define MESHAREACALCULATOR_H_INCLUDED #include "OgreNewt.h" #include <Ogre.h> namespace VD { class MeshAreaCalculator { public: Ogre::Vector3 windDir; float area; static void calculateArea(void* userData, int vertexCount, const float* faceVertices, int id); float calculateArea(OgreNewt::Body* body); }; } // namespace VD #endif // MESHAREACALCULATOR_H_INCLUDED

Code: Select all: #include "MeshAreaCalculator.h" namespace VD { void MeshAreaCalculator::calculateArea(void* userData, int vertexCount, const float* faceVertices, int id) { Ogre::Vector3 area(0.0f, 0.0f, 0.0f); Ogre::Vector3 p0(faceVertices[0 * 3 + 0], faceVertices[0 * 3 + 1], faceVertices[0 * 3 + 2]); Ogre::Vector3 p1(faceVertices[1 * 3 + 1], faceVertices[1 * 3 + 1], faceVertices[1 * 3 + 2]); Ogre::Vector3 dp0(p1 - p0); for(int i = 2; i < vertexCount; i++) { Ogre::Vector3 p1(faceVertices[i * 3 + 0], faceVertices[i * 3 + 1], faceVertices[i * 3 + 2]); Ogre::Vector3 dp1(p1 - p0); area += dp1 * dp0; dp0 = dp1; } MeshAreaCalculator* areaInfo = (MeshAreaCalculator*)userData; Ogre::Real value = area.dotProduct(areaInfo->windDir); if(value > 0.0f) { areaInfo->area += value; } } float MeshAreaCalculator::calculateArea(OgreNewt::Body* body) { windDir = body->getVelocity(); float matrix[16]; NewtonBodyGetMatrix(body->getNewtonBody(), &matrix[0]); float squaredMagnitude = windDir.squaredLength(); if(squaredMagnitude > 0.1f) { windDir.normalise(); NewtonCollisionForEachPolygonDo(NewtonBodyGetCollision(body->getNewtonBody()), &matrix[0], calculateArea, this); } return area; } } // namespace VD

Perhaps you can spot something wrong with this

by **JernejL** » Fri Jul 17, 2009 6:34 am

what shape is the model you are testing this on?

by **kallaspriit** » Fri Jul 17, 2009 6:43 am

Convex collision, does it matter?

Damping dependency of framerate

Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

Re: Damping dependency of framerate

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