Forcing Chipmunk to use floats

[Latexi95]

Is there any way to force Chipmunk to use floats instead of doubles? If I define CP_USE_DOUBLES to 0 in chipmunk_types.h Visual Studio 2010 gives me these kind of warning:

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Warning	40	warning C4789: destination of memory copy is too small	chipmunk-6.0.2\src\cpspace.c	line 129

and if I try to create body application will crash. Everything works fine when I don't define CP_USE_DOUBLES.

Btw, I would be nice, if Chipmunk's bodies had some kind of "bullet mode" (Box2D's bodies have), so they could go thought wall's when moving fast or timestep is high.

Sorry bad english.

[slembcke]

Setting CP_USE_DOUBLES to 0 should work. Maybe I messed something up somewhere though. I worked fine a couple months ago when I did some performance testing, and on the iPhone. Do you really want to use floats instead of doubles on a desktop CPU? Even on an Atom processor, doubles will make the computations faster as the CPU needs to convert them to doubles while loading them into registers. Chipmunk doesn't use a lot of memory bandwidth so you don't have to worry about the extra size slowing you down.

Did you modify cpSpace.c? Line 129 is:

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	cpBodyInitStatic(&space->_staticBody);

I don't see why that would make the warning that it does.

Swept or "bullet" collisions are very expensive to perform. There's a reason why Chipmunk runs 3x faster than Box2D.

[Latexi95]

Thank you for the answer.

I didn't know that doubles work faster than floats. Coolbasic (programming language what for I'm doing this library) always uses floats, so I have to convert doubles to floats.

"CP_USE_DOUBLES 0" doesn't seem to work. I haven't changed that line. Warning has something to do with "CP_USE_DOUBLES 0" because it doesn't show up if I don't define it. But I think, I won't use floats...

Again one "BTW" question: Any idea how this is made?

[slembcke]

Hmm. Well I'll look into that when I get the time. It should work.

SPH == Smoothed Particle Hydrodynamics. This is a good paper on the subject:
http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

[Latexi95]

Thank you.

Problem might be in my code, because it is quite hard to debug dll, when you can't use debugger...
I try to create crash again in fully c++ application. I will post if I found the problem.

[Latexi95]

This goes even stranger... I tried "Hello Chipmunk" example.
If I compile it in release mode, it will work fine. But If I build in debug mode, "Access violation" will happen in body.c in cpBodyAddShape

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cpBodyAddShape(cpBody *body, cpShape *shape)
{
	cpShape *next = body->shapeList;
	if(next) next->prev = shape;   // <<<<----- here
	
	shape->next = next;
	body->shapeList = shape;
}

and program print to console:

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Aborting due to Chipmunk error: This shape is already added to a space and canno
t be added to another.
        Failed condition: !shape->space

[/size]

But if I add line

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#define CP_USE_DOUBLES 0

before including chipmunk.h and I build in debug mode, program will work correctly.
And If I then (with "CP_USE_DOUBLES 0") build it in release mode, "Access violation" will happen at line

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cpShapeSetFriction(ground, 1);

I'm using VS2010 and I downloaded latest Chipmunk release and I built it using vs2010 solution file.

Edit: Okey... I think, I somehow built using old library version or something...
Now without "CP_USE_DOUBLES 0" debug mode works fine. But "CP_USE_DOUBLES 0" and release build mode combination still crashes.

Edit2: If I remove static "ground" body, program doesn't crash, but ballBody's position won't change (it's (-1.#J,0.0) ) and vertical velocity is very high (-0.00, 160801377226902880000000000000000000000.00).