Please Help 2D question - GameCreators Forum

Author

Message

Poof Master

14

Years of Service

User Offline

Joined: 14th Jan 2010

Location:

Posted: 4th Feb 2010 01:22

Link

Okay so here is my problem:

dbSpriteWidth and height are supposed to return the value of whatever the given sprite is. The problem is when I use it in this function it doesn't work:

+ Code Snippet

groundShapeDef.SetAsBox((dbSpriteWidth(1)/b2PixelRatio)/2.0f, (dbSpriteHeight(1)/b2PixelRatio)/2.0f);

I have tried to set the variable equal to dbSpriteWidth and height but the value of that varible is either 0 or -1 when I use the window watcher.

The weird thing is when I use the function dbSpriteOffset like so:

+ Code Snippet

dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);

the value of dbSpriteWidth and height are then equal to the actual value of the sprite I made. (which is 90)

Here's the full code I commented the points where I am trying to use dbSpriteWidth and Height and commented on there values at those points in program.

// whenever using Dark GDK you must include the header file
#include "Box2D.h"
#include "Render.h"
#include "DarkGDK.h"

#define b2PixelRatio 30.0f
#define b2PixelToMeter(n) ((n)/b2PixelRatio)
#define b2MeterToPixel(n) ((n)*b2PixelRatio)
#define b2PixelToHalfMeter(n) (((n)/b2PixelRatio)/2)
#define b2HalfMeterToPixel(n) (((n)*b2PixelRatio)*2)

int wPosX = 0;
int wPosY = 0;

// the main entry point for the application is this function
void DarkGDK ( void )
{
	dbLoadImage("ground.png",1);

dbLoadImage("character.png",2);

dbSetDisplayMode (960 ,720, 32);
	dbSetWindowPosition(wPosX,wPosY);

//////Box2d World Set UP///////
	b2AABB worldAABB;
	worldAABB.lowerBound.Set(wPosX,wPosY); 
	worldAABB.upperBound.Set(dbScreenWidth()/b2PixelRatio, dbScreenHeight()/b2PixelRatio);
	b2Vec2 gravity(0.0f, 9.0f);
	bool doSleep = false;
	b2World world(worldAABB, gravity, doSleep);

///////////////////////////////// Static Object/////////////////////////////////

b2BodyDef groundBodyDef;

groundBodyDef.position.Set(480 / b2PixelRatio,600 / b2PixelRatio);

b2Body* groundBody = world.CreateBody(&groundBodyDef);

b2PolygonDef groundShapeDef;

groundShapeDef.SetAsBox((dbSpriteWidth(1)/b2PixelRatio)/2.0f, (dbSpriteHeight(1)/b2PixelRatio)/2.0f);/////// dbSpriteWidth after this point is equal to 0 or -1////////

groundBody->CreateShape(&groundShapeDef);

/////////////////////////////////Rigid Body///////////////////////////////////

b2BodyDef playerBodyDef;

playerBodyDef.position.Set(320 / b2PixelRatio, 100 / b2PixelRatio);

b2Body* playerBody = world.CreateBody(&playerBodyDef);

b2PolygonDef playerShapeDef;

playerShapeDef.SetAsBox((dbSpriteWidth(2)/b2PixelRatio)/2.0f, (dbSpriteHeight(2)/b2PixelRatio)/2.0f);
	playerShapeDef.density = 1.0f;
	playerShapeDef.friction = 0.3f;
	playerBody->CreateShape(&playerShapeDef);
	playerBody->SetMassFromShapes();

playerBody->CreateShape(&playerShapeDef);

dbSyncOn ( );

dbSyncRate ( 60 );

while ( LoopGDK ( ) )
	{

float32 timeStep = 1.0f / 60.0f;
	 int32 iterations = 10;
     world.Step(timeStep, iterations);

///////////////////////////////// Static Object/////////////////////////////////
		
		float32 angle = groundBody->GetAngle();
		b2Vec2 position = groundBody->GetPosition();
		position.x *= b2PixelRatio;
		position.y *= b2PixelRatio;
		angle *= (180.0 / 3.141592653589793238);
		dbSprite(1,position.x,position.y,1);
		dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);///////////dbSpriteWidth after this point is equal to 90 which is the actual width of my sprite//////
		dbPasteSprite(1,position.x,position.y);
		dbRotateSprite(1, angle);

/////////////////////////////////Rigid Body///////////////////////////////////

float32 playerAngle = playerBody->GetAngle();
		b2Vec2 playerPosition = playerBody->GetPosition();
		playerPosition.x *= b2PixelRatio;
		playerPosition.y *= b2PixelRatio;
		playerAngle *= (180.0 / 3.141592653589793238);
		dbSprite(2,playerPosition.x,playerPosition.y,2);
		dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);
		dbPasteSprite(2,playerPosition.x,playerPosition.y);
		dbRotateSprite(2, playerAngle);

dbSync ( );
	}

// return back to windows
	return;
}

+ Code Snippet

// whenever using Dark GDK you must include the header file
#include "Box2D.h"
#include "Render.h"
#include "DarkGDK.h"

#define b2PixelRatio 30.0f
#define b2PixelToMeter(n) ((n)/b2PixelRatio)
#define b2MeterToPixel(n) ((n)*b2PixelRatio)
#define b2PixelToHalfMeter(n) (((n)/b2PixelRatio)/2)
#define b2HalfMeterToPixel(n) (((n)*b2PixelRatio)*2)



int wPosX = 0;
int wPosY = 0;

	
// the main entry point for the application is this function
void DarkGDK ( void )
{
	dbLoadImage("ground.png",1);

	dbLoadImage("character.png",2);


	
	
	


	dbSetDisplayMode (960 ,720, 32);
	dbSetWindowPosition(wPosX,wPosY);

//////Box2d World Set UP///////
	b2AABB worldAABB;
	worldAABB.lowerBound.Set(wPosX,wPosY); 
	worldAABB.upperBound.Set(dbScreenWidth()/b2PixelRatio, dbScreenHeight()/b2PixelRatio);
	b2Vec2 gravity(0.0f, 9.0f);
	bool doSleep = false;
	b2World world(worldAABB, gravity, doSleep);

///////////////////////////////// Static Object/////////////////////////////////

	b2BodyDef groundBodyDef;

	groundBodyDef.position.Set(480 / b2PixelRatio,600 / b2PixelRatio);

	b2Body* groundBody = world.CreateBody(&groundBodyDef);

	b2PolygonDef groundShapeDef;

	groundShapeDef.SetAsBox((dbSpriteWidth(1)/b2PixelRatio)/2.0f, (dbSpriteHeight(1)/b2PixelRatio)/2.0f);/////// dbSpriteWidth after this point is equal to 0 or -1////////

	groundBody->CreateShape(&groundShapeDef);



/////////////////////////////////Rigid Body///////////////////////////////////
	

	b2BodyDef playerBodyDef;

	playerBodyDef.position.Set(320 / b2PixelRatio, 100 / b2PixelRatio);

	b2Body* playerBody = world.CreateBody(&playerBodyDef);

	b2PolygonDef playerShapeDef;

	playerShapeDef.SetAsBox((dbSpriteWidth(2)/b2PixelRatio)/2.0f, (dbSpriteHeight(2)/b2PixelRatio)/2.0f);
	playerShapeDef.density = 1.0f;
	playerShapeDef.friction = 0.3f;
	playerBody->CreateShape(&playerShapeDef);
	playerBody->SetMassFromShapes();

	playerBody->CreateShape(&playerShapeDef);

	

	dbSyncOn ( );


	dbSyncRate ( 60 );



	while ( LoopGDK ( ) )
	{
		
		
	

	 float32 timeStep = 1.0f / 60.0f;
	 int32 iterations = 10;
     world.Step(timeStep, iterations);

	 ///////////////////////////////// Static Object/////////////////////////////////
		
		float32 angle = groundBody->GetAngle();
		b2Vec2 position = groundBody->GetPosition();
		position.x *= b2PixelRatio;
		position.y *= b2PixelRatio;
		angle *= (180.0 / 3.141592653589793238);
		dbSprite(1,position.x,position.y,1);
		dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);///////////dbSpriteWidth after this point is equal to 90 which is the actual width of my sprite//////
		dbPasteSprite(1,position.x,position.y);
		dbRotateSprite(1, angle);

		/////////////////////////////////Rigid Body///////////////////////////////////

		float32 playerAngle = playerBody->GetAngle();
		b2Vec2 playerPosition = playerBody->GetPosition();
		playerPosition.x *= b2PixelRatio;
		playerPosition.y *= b2PixelRatio;
		playerAngle *= (180.0 / 3.141592653589793238);
		dbSprite(2,playerPosition.x,playerPosition.y,2);
		dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);
		dbPasteSprite(2,playerPosition.x,playerPosition.y);
		dbRotateSprite(2, playerAngle);
  

		dbSync ( );
	}

	// return back to windows
	return;
}

So not to sure whats going on anyone have an idea?

Back to top

Profile PM

WH8

15

Years of Service

User Offline

Joined: 17th Mar 2009

Location:

Posted: 4th Feb 2010 06:22 Edited at: 4th Feb 2010 06:27

Link

I am not 100% certain of the problem, but it looks like you are calling dbSpriteWidth() and dbSpriteHeight() for a sprite that does not exist yet? The reason the two functions "work" at dbOffsetSprite() is because you just created sprite number 1 right before using those two functions, while at the first location where the two functions do not "work", sprite number 1 does not exist yet. From what I can see, this is the probem. Sprite number 2 looks like it is also experiencing the same problem. I am guessing you are getting 0 or -1 from those two functions because you are asking them to give you the width or the height of a sprite that does not yet exist.

Back to top

Profile PM

Poof Master

14

Years of Service

User Offline

Joined: 14th Jan 2010

Location:

Posted: 4th Feb 2010 07:37

Link

Yeah I guess dbSpriteWidth and Height are based off the function dbSprite() so I was calling that function in my main loop but I wasn't calling it above. The one thing about that then is it okay for me to call that function in two different places. I say this because of how things are initialized:

this is in my main loop:

+ Code Snippet

///////////////////////////////// Static Object/////////////////////////////////
		
		float32 angle = groundBody->GetAngle();
		b2Vec2 position = groundBody->GetPosition();
		position.x *= b2PixelRatio;
		position.y *= b2PixelRatio;
		angle *= (180.0 / 3.141592653589793238);
		dbSprite(1,position.x,position.y,1);
		//dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);
		dbPasteSprite(1,position.x,position.y);
		dbRotateSprite(1, angle);

The position is initialized in this loop so in order for my sprite to have the same position as the 2d physics box I had to call dbSprite in this loop rather than up in the main entry point.

So is there any harm in calling that function in both places cause this is how I have it now:

// the main entry point for the application is this function
void DarkGDK ( void )
{

dbSetDisplayMode (960 ,720, 32);
	dbSetWindowPosition(wPosX,wPosY);

//////Box2d World Set UP///////
	b2AABB worldAABB;
	worldAABB.lowerBound.Set(wPosX,wPosY); 
	worldAABB.upperBound.Set(dbScreenWidth()/b2PixelRatio, dbScreenHeight()/b2PixelRatio);
	b2Vec2 gravity(0.0f, 9.0f);
	bool doSleep = false;
	b2World world(worldAABB, gravity, doSleep);

///////////////////////////////// Static Object/////////////////////////////////

dbLoadImage("ground.png",1);
dbSprite(1,0,0,1);
dbLoadImage("character.png",2);
dbSprite(2,0,0,2);
dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);
dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);

b2BodyDef groundBodyDef;

groundBodyDef.position.Set(480 / b2PixelRatio,600 / b2PixelRatio);

b2Body* groundBody = world.CreateBody(&groundBodyDef);

b2PolygonDef groundShapeDef;

groundShapeDef.SetAsBox((dbSpriteWidth(1)/b2PixelRatio)/2.0f, (dbSpriteHeight(1)/b2PixelRatio)/2.0f);

groundBody->CreateShape(&groundShapeDef);

/////////////////////////////////Rigid Body///////////////////////////////////

b2BodyDef playerBodyDef;

playerBodyDef.position.Set(320  / b2PixelRatio, 100 / b2PixelRatio);

b2Body* playerBody = world.CreateBody(&playerBodyDef);

b2PolygonDef playerShapeDef;

playerShapeDef.SetAsBox((dbSpriteWidth(2)/b2PixelRatio)/2.0f, (dbSpriteHeight(2)/b2PixelRatio)/2.0f);
	playerShapeDef.density = 1.0f;
	playerShapeDef.friction = 0.3f;
	playerBody->CreateShape(&playerShapeDef);
	playerBody->SetMassFromShapes();

playerBody->CreateShape(&playerShapeDef);

dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);

dbSyncOn ( );

dbSyncRate ( 60 );

while ( LoopGDK ( ) )
	{
		
	
	 float32 timeStep = 1.0f / 60.0f;
	 int32 iterations = 10;
     world.Step(timeStep, iterations);

///////////////////////////////// Static Object/////////////////////////////////
		
		float32 angle = groundBody->GetAngle();
		b2Vec2 position = groundBody->GetPosition();
		position.x *= b2PixelRatio;
		position.y *= b2PixelRatio;
		angle *= (180.0 / 3.141592653589793238);
		dbSprite(1,position.x,position.y,1);
		//dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);
		dbPasteSprite(1,position.x,position.y);
		dbRotateSprite(1, angle);

/////////////////////////////////Rigid Body///////////////////////////////////

float32 playerAngle = playerBody->GetAngle();
		b2Vec2 playerPosition = playerBody->GetPosition();
		playerPosition.x *= b2PixelRatio;
		playerPosition.y *= b2PixelRatio;
		playerAngle *= (180.0 / 3.141592653589793238);
		dbSprite(2,playerPosition.x,playerPosition.y,2);
		//dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);
		dbPasteSprite(2,playerPosition.x,playerPosition.y);
		dbRotateSprite(2, playerAngle);
  
		dbSync ( );
	}

// return back to windows
	return;
}

+ Code Snippet

// the main entry point for the application is this function
void DarkGDK ( void )
{




	dbSetDisplayMode (960 ,720, 32);
	dbSetWindowPosition(wPosX,wPosY);

//////Box2d World Set UP///////
	b2AABB worldAABB;
	worldAABB.lowerBound.Set(wPosX,wPosY); 
	worldAABB.upperBound.Set(dbScreenWidth()/b2PixelRatio, dbScreenHeight()/b2PixelRatio);
	b2Vec2 gravity(0.0f, 9.0f);
	bool doSleep = false;
	b2World world(worldAABB, gravity, doSleep);

///////////////////////////////// Static Object/////////////////////////////////

dbLoadImage("ground.png",1);
dbSprite(1,0,0,1);
dbLoadImage("character.png",2);
dbSprite(2,0,0,2);
dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);
dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);


	b2BodyDef groundBodyDef;

	groundBodyDef.position.Set(480 / b2PixelRatio,600 / b2PixelRatio);

	b2Body* groundBody = world.CreateBody(&groundBodyDef);

	b2PolygonDef groundShapeDef;

	groundShapeDef.SetAsBox((dbSpriteWidth(1)/b2PixelRatio)/2.0f, (dbSpriteHeight(1)/b2PixelRatio)/2.0f);

	groundBody->CreateShape(&groundShapeDef);




/////////////////////////////////Rigid Body///////////////////////////////////
	

		b2BodyDef playerBodyDef;

	playerBodyDef.position.Set(320  / b2PixelRatio, 100 / b2PixelRatio);

	b2Body* playerBody = world.CreateBody(&playerBodyDef);

	b2PolygonDef playerShapeDef;

	playerShapeDef.SetAsBox((dbSpriteWidth(2)/b2PixelRatio)/2.0f, (dbSpriteHeight(2)/b2PixelRatio)/2.0f);
	playerShapeDef.density = 1.0f;
	playerShapeDef.friction = 0.3f;
	playerBody->CreateShape(&playerShapeDef);
	playerBody->SetMassFromShapes();

	playerBody->CreateShape(&playerShapeDef);

	
	
	dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);


	dbSyncOn ( );

	dbSyncRate ( 60 );

	while ( LoopGDK ( ) )
	{
		
	
	 float32 timeStep = 1.0f / 60.0f;
	 int32 iterations = 10;
     world.Step(timeStep, iterations);

	 ///////////////////////////////// Static Object/////////////////////////////////
		
		float32 angle = groundBody->GetAngle();
		b2Vec2 position = groundBody->GetPosition();
		position.x *= b2PixelRatio;
		position.y *= b2PixelRatio;
		angle *= (180.0 / 3.141592653589793238);
		dbSprite(1,position.x,position.y,1);
		//dbOffsetSprite(1, dbSpriteWidth(1)/2,dbSpriteHeight(1)/2);
		dbPasteSprite(1,position.x,position.y);
		dbRotateSprite(1, angle);

		/////////////////////////////////Rigid Body///////////////////////////////////

		float32 playerAngle = playerBody->GetAngle();
		b2Vec2 playerPosition = playerBody->GetPosition();
		playerPosition.x *= b2PixelRatio;
		playerPosition.y *= b2PixelRatio;
		playerAngle *= (180.0 / 3.141592653589793238);
		dbSprite(2,playerPosition.x,playerPosition.y,2);
		//dbOffsetSprite(2, dbSpriteWidth(2)/2,dbSpriteHeight(2)/2);
		dbPasteSprite(2,playerPosition.x,playerPosition.y);
		dbRotateSprite(2, playerAngle);
  
		dbSync ( );
	}

	// return back to windows
	return;
}

Is there a better way or am I just going to have to call it twice?

Back to top

Profile PM

WH8

15

Years of Service

User Offline

Joined: 17th Mar 2009

Location:

Posted: 5th Feb 2010 04:15 Edited at: 5th Feb 2010 04:31

Link

Remember that you create a sprite using dbSprite(). No sprite is created with dbLoadImage(). All dbLoadImage() does is put a picture into memory so that later on in your program that picture can be "used". Until dbSprite() is called, the sprite does not exist. Trying to find the width and height of a non-existing sprite will not give the width and height of the sprite that you want to exist. In other words, you MUST use dbSprite() for your sprites 1 and 2 before trying to find their widths or heights with dbSpriteWidth() and dbSpriteHeight().

You can call dbSprite() for any sprite as many times as you like. dbSprite() is not only used to create sprites, but to reposition existing sprites as well. If you want to change the image of a sprite, you might need to use dbSetSpriteImage().

There is a documentation on some of the Dark GDK functions that you can find roughly in: C:\Program Files\The Game Creators\Dark GDK\Documentation.

Back to top

Profile PM

Poof Master

14

Years of Service

User Offline

Joined: 14th Jan 2010

Location:

Posted: 6th Feb 2010 07:19

Link

Yeah I understand now. Thanks for the help I guess my next task is to put all that code into a class so I can just call an initialize and update function for any new boxes I want to create but anyway thanks for the explanation.

Back to top

Profile PM

Sorry your browser is not supported!

Dark GDK / Please Help 2D question