Making the object understand how much it should rotate based on the target position

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jontepd

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Joined: 24th Feb 2009

Location: Sweden

Posted: 9th Mar 2009 16:13

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In the code i have, i have an object (a tank) which moves to where you right click with your mouse. However a tank can not move sideways so for example if the tank is going far to the left, but not up or down at all, it needs to rotate 90 degrees before it moves. If it's going up and a little to the right the rotation is different. How do i make the object understand how much it is supposed to rotate based on the target position?

#include "DarkGDK.h"

// the main entry point for the application is this function
void DarkGDK ( void )
{
	// turn on sync rate and set maximum rate to 60 fps
	dbSyncOn   ( );
	dbSyncRate ( 60 );

dbAutoCamOff();

dbMaximizeWindow();

dbLoadObject("map.x", 2);
	int map = 2;
	dbPositionObject(map, 0, 600, 300);
	dbScaleObject(map, 1000, 1000, 1000);
	dbColorObject(map, 255);

dbLoadObject("tank.x", 1);
	int tank = 1;
	dbRotateCamera(0, 0, 0);
	dbPositionCamera(0, 0, -2000);

float xHit;
	float yHit;
	bool objectPlaced = false;
	bool targetPlaced = false;

// our main loop
	while ( LoopGDK ( ) )
	{	
		if (dbMouseClick() == 2)
		{
			dbPickObject( dbMouseX (), dbMouseY (), map, map );

xHit = dbGetPickVectorX() + dbCameraPositionX();
			yHit = dbGetPickVectorY() + dbCameraPositionY();

targetPlaced = true;
		}
		if (targetPlaced == true)
		{
			if (dbObjectPositionY(tank) < yHit)
			{
				dbMoveObjectUp(tank, 1);
			}
			if (dbObjectPositionY(tank) > yHit)
			{
				dbMoveObjectDown(tank, 1);
			}
			if (dbObjectPositionX(tank) < xHit)
			{
				dbMoveObjectRight(tank, 1);
			}
			if (dbObjectPositionX(tank) > xHit)
			{
				dbMoveObjectLeft(tank, 1);
			}
		}
		if (dbObjectPositionY(tank) >= yHit -50 && dbObjectPositionY(tank) <= yHit +50
			&& dbObjectPositionX(tank) >= xHit -50 && dbObjectPositionX(tank) <= xHit +50)
		{
			dbText(250, 250, "Position Matches.");
			targetPlaced = false;
		}
		// update the screen
		dbSync ( );
	}

// return back to windows
	return;
}

+ Code Snippet

#include "DarkGDK.h"

// the main entry point for the application is this function
void DarkGDK ( void )
{
	// turn on sync rate and set maximum rate to 60 fps
	dbSyncOn   ( );
	dbSyncRate ( 60 );

	dbAutoCamOff();

	dbMaximizeWindow();

	dbLoadObject("map.x", 2);
	int map = 2;
	dbPositionObject(map, 0, 600, 300);
	dbScaleObject(map, 1000, 1000, 1000);
	dbColorObject(map, 255);

	dbLoadObject("tank.x", 1);
	int tank = 1;
	dbRotateCamera(0, 0, 0);
	dbPositionCamera(0, 0, -2000);

	float xHit;
	float yHit;
	bool objectPlaced = false;
	bool targetPlaced = false;

	// our main loop
	while ( LoopGDK ( ) )
	{	
		if (dbMouseClick() == 2)
		{
			dbPickObject( dbMouseX (), dbMouseY (), map, map );

			xHit = dbGetPickVectorX() + dbCameraPositionX();
			yHit = dbGetPickVectorY() + dbCameraPositionY();

			targetPlaced = true;
		}
		if (targetPlaced == true)
		{
			if (dbObjectPositionY(tank) < yHit)
			{
				dbMoveObjectUp(tank, 1);
			}
			if (dbObjectPositionY(tank) > yHit)
			{
				dbMoveObjectDown(tank, 1);
			}
			if (dbObjectPositionX(tank) < xHit)
			{
				dbMoveObjectRight(tank, 1);
			}
			if (dbObjectPositionX(tank) > xHit)
			{
				dbMoveObjectLeft(tank, 1);
			}
		}
		if (dbObjectPositionY(tank) >= yHit -50 && dbObjectPositionY(tank) <= yHit +50
			&& dbObjectPositionX(tank) >= xHit -50 && dbObjectPositionX(tank) <= xHit +50)
		{
			dbText(250, 250, "Position Matches.");
			targetPlaced = false;
		}
		// update the screen
		dbSync ( );
	}

	// return back to windows
	return;
}

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silenus

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Joined: 4th Mar 2009

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Posted: 9th Mar 2009 16:33

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lets say target position is x=200 z=500
Your position is x=500 z=900
your x minus target x is 500-200=300=delta_x
your z minus target z is 900-500=400=delta_z
the angle is than: dbTAN(delta_x/delta_z)

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AlexZinn

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Joined: 17th Feb 2009

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Posted: 9th Mar 2009 17:18

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em... if its a 2d game... to get angle the only wait its use tan-1

i making now a library that makes it good for 2d..

you need the distance from mouse to the tank..(Y) divide the distance of the mouse from tank (X) and tan-1.. it is in the math.h library..
atan(x)

If someone need something, add me to your msn

Was SuperKid , now AlexZinn

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jontepd

15

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Joined: 24th Feb 2009

Location: Sweden

Posted: 9th Mar 2009 17:56

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I'm a bit unsure how to use the dbTAN thing, would be great with some help. This is what i have so far but it's not working (no conversion from 'float (__cdecl *)(float)' to 'float')

#include "DarkGDK.h"

// the main entry point for the application is this function
void DarkGDK ( void )
{
	// turn on sync rate and set maximum rate to 60 fps
	dbSyncOn   ( );
	dbSyncRate ( 60 );

dbAutoCamOff();

dbMaximizeWindow();

dbLoadObject("map.x", 2);
	int map = 2;
	dbPositionObject(map, 0, 600, 300);
	dbScaleObject(map, 1000, 1000, 1000);
	dbColorObject(map, 255);

dbLoadObject("tank.x", 1);
	int tank = 1;
	dbRotateCamera(0, 0, 0);
	dbPositionCamera(0, 0, -2000);

float xHit;
	float yHit;
	bool objectPlaced = false;
	bool targetPlaced = false;

float delta_x;
	float delta_y;

// our main loop
	while ( LoopGDK ( ) )
	{	
		if (dbMouseClick() == 2)
		{
			dbPickObject( dbMouseX (), dbMouseY (), map, map );

xHit = dbGetPickVectorX() + dbCameraPositionX();
			yHit = dbGetPickVectorY() + dbCameraPositionY();

targetPlaced = true;
		}
		if (targetPlaced == true)
		{
			delta_x = dbObjectPositionX(tank) - xHit;
			delta_y = dbObjectPositionY(tank) - yHit;
			dbTAN(delta_x/delta_y);
			
			if (dbObjectAngleZ(tank) == dbTan)
			{
				dbText(250, 300, "Rotated.");
			}
			else
			{
				dbRotateObject(tank, dbObjectAngleX(tank), dbObjectAngleY(tank), dbObjectAngleZ(tank) + 0.5);
			}
			/*if (dbObjectPositionY(tank) < yHit)
			{
				dbMoveObjectUp(tank, 1);
			}
			if (dbObjectPositionY(tank) > yHit)
			{
				dbMoveObjectDown(tank, 1);
			}
			if (dbObjectPositionX(tank) < xHit)
			{
				dbMoveObjectRight(tank, 1);
			}
			if (dbObjectPositionX(tank) > xHit)
			{
				dbMoveObjectLeft(tank, 1);
			}*/
		}
		if (dbObjectPositionY(tank) >= yHit -50 && dbObjectPositionY(tank) <= yHit +50
			&& dbObjectPositionX(tank) >= xHit -50 && dbObjectPositionX(tank) <= xHit +50)
		{
			dbText(250, 250, "Position Matches.");
			targetPlaced = false;
		}
		// update the screen
		dbSync ( );
	}

// return back to windows
	return;
}

+ Code Snippet

#include "DarkGDK.h"

// the main entry point for the application is this function
void DarkGDK ( void )
{
	// turn on sync rate and set maximum rate to 60 fps
	dbSyncOn   ( );
	dbSyncRate ( 60 );

	dbAutoCamOff();

	dbMaximizeWindow();

	dbLoadObject("map.x", 2);
	int map = 2;
	dbPositionObject(map, 0, 600, 300);
	dbScaleObject(map, 1000, 1000, 1000);
	dbColorObject(map, 255);

	dbLoadObject("tank.x", 1);
	int tank = 1;
	dbRotateCamera(0, 0, 0);
	dbPositionCamera(0, 0, -2000);

	float xHit;
	float yHit;
	bool objectPlaced = false;
	bool targetPlaced = false;

	float delta_x;
	float delta_y;

	// our main loop
	while ( LoopGDK ( ) )
	{	
		if (dbMouseClick() == 2)
		{
			dbPickObject( dbMouseX (), dbMouseY (), map, map );

			xHit = dbGetPickVectorX() + dbCameraPositionX();
			yHit = dbGetPickVectorY() + dbCameraPositionY();

			targetPlaced = true;
		}
		if (targetPlaced == true)
		{
			delta_x = dbObjectPositionX(tank) - xHit;
			delta_y = dbObjectPositionY(tank) - yHit;
			dbTAN(delta_x/delta_y);
			
			if (dbObjectAngleZ(tank) == dbTan)
			{
				dbText(250, 300, "Rotated.");
			}
			else
			{
				dbRotateObject(tank, dbObjectAngleX(tank), dbObjectAngleY(tank), dbObjectAngleZ(tank) + 0.5);
			}
			/*if (dbObjectPositionY(tank) < yHit)
			{
				dbMoveObjectUp(tank, 1);
			}
			if (dbObjectPositionY(tank) > yHit)
			{
				dbMoveObjectDown(tank, 1);
			}
			if (dbObjectPositionX(tank) < xHit)
			{
				dbMoveObjectRight(tank, 1);
			}
			if (dbObjectPositionX(tank) > xHit)
			{
				dbMoveObjectLeft(tank, 1);
			}*/
		}
		if (dbObjectPositionY(tank) >= yHit -50 && dbObjectPositionY(tank) <= yHit +50
			&& dbObjectPositionX(tank) >= xHit -50 && dbObjectPositionX(tank) <= xHit +50)
		{
			dbText(250, 250, "Position Matches.");
			targetPlaced = false;
		}
		// update the screen
		dbSync ( );
	}

	// return back to windows
	return;
}

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AlexZinn

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Joined: 17th Feb 2009

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Posted: 9th Mar 2009 18:29

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first of all i dont talking about dbTan

we need tan-1
try this

#include <math.h>
alpha1 = altan(x);
alpha2 = (2,(alpha1* 180) / 3.14);

so if X = -1
alpha1 = -0.78538 (radians so)
alpha 2 = -45

If someone need something, add me to your msn

Was SuperKid , now AlexZinn

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jontepd

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Joined: 24th Feb 2009

Location: Sweden

Posted: 9th Mar 2009 18:32

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Yeah but you said if it's a 2d game, but the game is in 3d

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silenus

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Joined: 4th Mar 2009

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Posted: 9th Mar 2009 19:06

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I said dbTAN, but Alex is right u need Tan-1
and thats it:

Quote: "dbATANFULL
This command will return the angle of two points in degrees between 0 and 360. The distance values are calculated by finding the distance between two points for both the X and Y axis.

Syntax
float dbATANFULL ( float fX, float fY )"

I think in my example you should use it this way:

dbATANFULL ( delta_x, delta_y ;

And I am not sure wether this works:

+ Code Snippet

dbTAN(delta_x/delta_y);
			
			if (dbObjectAngleZ(tank) == dbTan)
			{
				dbText(250, 300, "Rotated.");
			}

I would use something like this:
float target_angle;

+ Code Snippet

target_angle=dbTAN(delta_x/delta_y);
			
			if (dbObjectAngleZ(tank) == target_angle)
			{
				dbText(250, 300, "Rotated.");
			}

And I think you need the angle around the Y axis, not dbObjectAngleZ(tank)
Further more, in your example it doesn't matter wether 2d or 3d, because your are just interessted in the angle around the Y-axis.

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Dark GDK / Making the object understand how much it should rotate based on the target position