Thread: Physics Engine Problem

I'm trying to make my own basic physics engine, featuring gravity, collision detection, and hopefully some ragdoll. This engine is made in directX 9 in case you didn't notice.

My problem is with the gravity function.

The function is called every millesecond from a timer.

Here is what it looks like:

Code:

void Phy_Gravity(LPDIRECT3DRMFRAME frScene, LPDIRECT3DRMFRAME Camera){
LPDIRECT3DRMFRAMEARRAY SceneArray;
FrameStruct frFrame;
D3DVECTOR vectPos;
int ArraySize;

frScene->GetChildren(&SceneArray);
ArraySize = SceneArray->GetSize();

	for (int i = 0; i < ArraySize; i++){
	SceneArray->GetElement(i, &frFrame.frFrame);
	frFrame.frFrame->GetPosition(frScene, &vectPos);
		
		if (frFrame.frFrame != Camera){
		frFrame.frFrame->SetVelocity(frScene, 0, -frFrame.Weight, 0, false);
		}
	}
}

FrameStruct is a struct with three variables:

Code:

LPDIRECT3DRMFRAME frFrame
int Weight
int Bounce

You'll notice that if the frame being pulled is not the camera, then I want the object to go down on the y axis according to its own weight, which I defined when I created the frame.

I set the weight of the cube to 0.1, but I tried debugging and it shows me the weight as being -8.blah blah blah which is way to fast.

I think the problem is that the function does not get the weight variable when I do this:

Code:

SceneArray->GetElement(i, &frFrame.frFrame);

So it guesses the weight and puts it to a huge number, like -8.

How do I get my function to be able to use the weight variable?

GetElement is just a function included with the SDK, I have no idea where to find the code.

And as for the basic physics, I don't won't to go thorugh with anything too complicated, I think just using weight is realistic enough.