2D Platformer - Gravity & Jump - GameCreators Forum

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shadow sight

18

Years of Service

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Joined: 26th Oct 2006

Location: Derby England

Posted: 8th Feb 2010 17:40 Edited at: 8th Feb 2010 19:32

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Hey guys, I downloaded the Dark GDK again yesterday and I've set out to make a small Platformer.

What I want is to be able to Jump (Either with Physics or just "jump"ing)

I've tried Box2D and S3GE both to no prevail and so I tried to create the "jump" functionality for myself.

What I have so far is:

#include "Library.h"

float y = dbSpriteY(10);
int velocityY;
bool jumping = false;

void Controls()
{
	//Controls -- Directional Control Buttons

if(dbUpKey() == 1)
	{
		if(jumping == false)
		{
			y = dbSpriteY(10);
			jumping = true;
		}
	}

if (jumping == true && dbSpriteY(10) != y)  // Move Player if we are jumping 
	{
		do
		{
			dbMoveSprite(10,velocityY);
			velocityY = velocityY - 1;
		}while(y != dbSpriteY(10));
	}

if (dbSpriteY(10) <= y && jumping == true)     // Check to see if Player has hit floor
	{
		velocityY = 0;
		jumping = false;
	}

if(dbLeftKey() == 1)
	{
		dbSetSpriteFrame(10,3);
		dbRotateSprite(10,90);
		dbMoveSprite(10,-1);
		dbRotateSprite(10,0);

if(Collision() == true)
			{
				dbRotateSprite(10,90);
				dbMoveSprite(10,1);
				dbRotateSprite(10,0);
			}
		
	}

if(dbRightKey() == 1)
	{
		dbSetSpriteFrame(10,4);
		dbRotateSprite(10,90);
		dbMoveSprite(10,1);
		dbRotateSprite(10,0);
		
			if(Collision() == true)
			{
				dbRotateSprite(10,90);
				dbMoveSprite(10,-1);
				dbRotateSprite(10,0);
			}
	}

if(dbDownKey() == 1)
	{
		dbSetSpriteFrame(10,1);
		dbMoveSprite(10,-1);

if(Collision() == true)
		{
			dbMoveSprite(10,1);
		}
	}

}

+ Code Snippet

#include "Library.h"

float y = dbSpriteY(10);
int velocityY;
bool jumping = false;

void Controls()
{
	//Controls -- Directional Control Buttons

	if(dbUpKey() == 1)
	{
		if(jumping == false)
		{
			y = dbSpriteY(10);
			jumping = true;
		}
	}

	if (jumping == true && dbSpriteY(10) != y)  // Move Player if we are jumping 
	{
		do
		{
			dbMoveSprite(10,velocityY);
			velocityY = velocityY - 1;
		}while(y != dbSpriteY(10));
	}

	if (dbSpriteY(10) <= y && jumping == true)     // Check to see if Player has hit floor
	{
		velocityY = 0;
		jumping = false;
	}

	if(dbLeftKey() == 1)
	{
		dbSetSpriteFrame(10,3);
		dbRotateSprite(10,90);
		dbMoveSprite(10,-1);
		dbRotateSprite(10,0);

			if(Collision() == true)
			{
				dbRotateSprite(10,90);
				dbMoveSprite(10,1);
				dbRotateSprite(10,0);
			}
		
	}

	if(dbRightKey() == 1)
	{
		dbSetSpriteFrame(10,4);
		dbRotateSprite(10,90);
		dbMoveSprite(10,1);
		dbRotateSprite(10,0);
		
			if(Collision() == true)
			{
				dbRotateSprite(10,90);
				dbMoveSprite(10,-1);
				dbRotateSprite(10,0);
			}
	}

	if(dbDownKey() == 1)
	{
		dbSetSpriteFrame(10,1);
		dbMoveSprite(10,-1);

		if(Collision() == true)
		{
			dbMoveSprite(10,1);
		}
	} 

}

This compiles fine but doesn't work.

If there's a fix for this or a different/easier way of doing things, please let me know.

Thanks
Lee

Founder of Fireball Games

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shadow sight

18

Years of Service

User Offline

Joined: 26th Oct 2006

Location: Derby England

Posted: 9th Feb 2010 00:02

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bump

I've been working on this ALL day today and the best I've managed is:

+ Code Snippet

void Controls()
{
	//Controls -- Jump

	if(dbUpKey() == 1)
	{
		while(dbUpKey()) { } // Waits until the button has been released so that it can continue with this.
		dbMoveSprite(10,10);
		InAir=true;
	}
}

+ Code Snippet

void Gravity()
{
	//dbSpriteY(10) >= dbSpriteY(11)+2
	if(!Collision() && InAir == true)
	{
		dbMoveSprite(10,-5);
		InAir = true;
	}

	if(Collision())
	{
		dbMoveSprite(10,1);
		InAir = false;
	}
}

This works to about 90% of what I want, except; The transition when jumping isn't smooth, obviously it just moves the sprite and when I've jumped it leaves me at the top of the jump. It doesn't take me back down.

Founder of Fireball Games

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Hassan

15

Years of Service

User Offline

Joined: 4th May 2009

Location: <script> alert(1); </script>

Posted: 9th Feb 2010 08:49

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maybe

+ Code Snippet

int yOffset = 0;
bool jumping = false;
void Controls ( void )
{
if ( jumpingkey() && !jumping )
{
jumping = true;
}
if ( jumping )
{
if ( yOffset < 10 )
yOffset++;
else
{
yOffset--;
if ( yOffset == 0 )
jumping = false;
}
}
dbSprite ( ID, X, Y+yOffset, img );
}

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shadow sight

18

Years of Service

User Offline

Joined: 26th Oct 2006

Location: Derby England

Posted: 12th Feb 2010 18:20

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I worked it out, I tried the methods that you posted but it didn't give me the desired outcome. So I sat down with the old pen and paper and came up with this.

Controls:

+ Code Snippet

if(dbUpKey())
	{
		if(!Falling())
		{
			dbMoveSprite(1,7);
			dbSync();
		}
	}

Physics:

+ Code Snippet


bool Collision()
{
	if(dbSpriteCollision(1,0) > 1 && dbSpriteCollision(1,0) < 10)
		return true;
	else
		return false;
}

bool Falling()
{
	if(dbSpriteCollision(1,0) > 1 && dbSpriteCollision(1,0) < 10)
		return false;
	else
		return true;
}

Lee Walker Founder of Fireball Games

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oika

14

Years of Service

User Offline

Joined: 16th Feb 2010

Location: Milky Way Galaxy

Posted: 16th Feb 2010 10:37

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Try this:
//very simple jumping procedure
//variable jump = 0
if (Space () && jump == JUMPIT) //global JUMPIT = 1234 or other value
jump = 18; //change this for your needs

//check for jumping or falling
if (jump != JUMPIT)
{
player.y -= jump / 3; //change this for your needs
jump --;
}
else
//check for collision with ground or what you have
// you can change if to switch to check collision with different types of obstackles and sprites
//here you can add code for detecting collision with the objects above the player
//player.w is player width and player.h is player height
if (!Collision (player.x + (player.w / 2), player.y + player.h) == BLOCK) /*||
(!Collision (player.x + (player.w / 2), player.y) == BLOCK)*/
jump = 0;

//if jump < 0, player is falling, check for collision with ground or what you have
if (jump < 0) //player is falling
{
// you can change if to switch to check collision with different types of obstackles and sprites
if (Collision (player.x + player.w / 2, player.y + player.h ) == BLOCK )

{
jump = JUMPIT;

while (Collision (player.x + player.w / 2, player.y + player.h) == BLOCK)
player.y -= 1;
}
}

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Dark GDK / 2D Platformer - Gravity & Jump

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Dark GDK / 2D Platformer - Gravity &amp; Jump

Dark GDK / 2D Platformer - Gravity & Jump