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Need Help to move (Solved)

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I want to add some physics to my car, at the moment i am just moving it by its forwardVector by a constant move_rate (#define MOVE_RATE 0.5f). This is my 1st time trying to add any physics to an object and i most learn by example, so if anyone could help me set up my movement functions for the car properly i can then play around and add friction to slow the car down. I know that: ======================================================= my forwardVector is my Velocity; Velocity = Velocity + accelerationVector * time; positionVector = positionVector + Velocity; acceleration = (currentVelocity - lastVelocity) / (currentTime - lastTime); ======================================================== Car.cpp
#define MOVE_RATE 0.5f

	//magnitude = 0.0f;
	ForwardVector.x = MOVE_RATE;
	turningRate = 2.0f;
	accelerationVector.x = 0.0f;
	accelerationVector.y = 0.0f;
	accelerationVector.z = 0.0f;



bool CCar::create(LPDIRECT3DDEVICE9 device)
	positionVector.x = 0.0f;
	positionVector.y = 0.0f;
	positionVector.z = 0.0f;

	ForwardVector.x = 0.0f;
	ForwardVector.y = 0.0f;
	ForwardVector.z = 1.0f;

	Model = new CModel();
	return Model->loadModel(device, "./models/car.x");

void CCar::setPosition(D3DXVECTOR3 newPosition)
	positionVector = newPosition;
void CCar::move(int direction)
	switch (direction)
	case FORWARD:
		ForwardVector.x = -MOVE_RATE;
		positionVector.x -= ForwardVector.x * -sin(D3DXToRadian(ForwardVector.y));
		positionVector.z += ForwardVector.x * cos(D3DXToRadian(ForwardVector.y));

		ForwardVector.x = MOVE_RATE;
		positionVector.x -= ForwardVector.x * -sin(D3DXToRadian(ForwardVector.y));
		positionVector.z += ForwardVector.x * cos(D3DXToRadian(ForwardVector.y));

	case LEFT:
		ForwardVector.y -= turningRate;

	case RIGHT:
		ForwardVector.y +=turningRate;

void CCar::update()
	/*Calculate the cars velocity by its magnitude (velocity = length of its vectors)
	// magnitude = (sqrt)((ForwardVector.x * ForwardVector.x) + (ForwardVector.y * ForwardVector.y) + (ForwardVector.z * ForwardVector.z));
	// D3DXVec3Normalize(&normVelocity,&ForwardVector);
	// ForwardVector = ForwardVector + accelerationVector * time;
	// positionVector = positionVector + ForwardVector;
	// acceleration = (currentVelocity - lastVelocity) / (currentTime - lastTime);

void CCar::render(LPDIRECT3DDEVICE9 device)
	D3DXMATRIX transMatrix;				// the translation matrix
	D3DXMATRIX rotMatrix;				// the rotation matrix
	D3DXMATRIX scaleMatrix;				// the scale matrix

	// create the translation matrix
	D3DXMatrixTranslation(&transMatrix, positionVector.x, positionVector.y, positionVector.z);

	// create the rotation matrix for the object

	// Scale the Car by the size amount
	D3DXMatrixScaling(&scaleMatrix, size, size, size);

	// Multiply the translation matrix by the rotation matrix
	// The resulting matrix is stored in the transMatrix
	D3DXMatrixMultiply(&transMatrix, &rotMatrix, &transMatrix);

	// Multiply the translation matrix by the scale
	D3DXMatrixMultiply(&transMatrix, &scaleMatrix, &transMatrix);

	// Transform the object into world space
	device->SetTransform(D3DTS_WORLD, &transMatrix);
	// render the model for this car
void CCar::setSize(float carSize)
	size = carSize;

class CModel;

class CCar : CGameObject

	void setSize(float carSize);

	// enumeration controlling the direction of the car
	enum { FORWARD=0, BACKWARD=1, LEFT=2, RIGHT=3 };

	// Overridden methods from the parent class
	bool create(LPDIRECT3DDEVICE9 device);
	void render(LPDIRECT3DDEVICE9 device);

	void setPosition(D3DXVECTOR3 newPosition);
	void move(int direction);
	void update();
	void create_Bounding_Box(LPDIRECT3DDEVICE9 device);

	// The current position of the car
	D3DXVECTOR3 positionVector;
	// The car's forward vector, what direction it is facing
	D3DXVECTOR3 ForwardVector;
	// The current acceleration of the car
	D3DXVECTOR3 accelerationVector;
	D3DXVECTOR3 normVelocity;

	float magnitude;
	float currentVelocity;
	float lastVelocity;
	float currentTime;
	float lastTime;

	CModel *Model;
	float	turningRate;

	// The size of the car
	float size;

	// The movement rate of the car
	float  moveRate;

[Edited by - Prog101 on November 10, 2006 4:00:21 AM]

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now what sort of physics do you want? have you tried rotation?

usually, for the sake of simplicity, i have a position vector, and velocity vector


then in the onFrame, step, or whatever you want to call it:

pos += vel;

for simple friction, i use a quick damping method in the step as well.




You can initialize vel to be the driection you want like:




I'm not sure if this is too baisc or inacurate for what you want?

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