alien jumping

Newbie & Debugging Questions
#1

Hi,

Tried implementing some code to make one of my aliens jump and when hit something above come straight back down until hit the floor.


private void jump() {
		Y = (float) (this.y - Math.sin(angle) * r);
		Vector3 pos = new Vector3(x,Y+8,0);
		if (jump) {// && !collisionUp) {
			if(this.worldMap.checkCollision(pos))   // check above 
			{					
				angle -= 0.04f;
            this.x += 1;
				pos = new Vector3(x,Y-8,0);
				if(!this.worldMap.checkCollision(pos)) { // collision below
					angle = 0;
				}
			}
		}
}

	public boolean checkCollision(Vector3 position) {
		Vector3 screenSpace = toScreenSpace(position);
		int x = Math.round(screenSpace.x);
		int y = Math.round(screenSpace.y);
		BlankEntity entity = getBlock(x, y);
		if (entity instanceof CaveTopEntity || entity instanceof CaveLeftEntity || entity instanceof CaveRightEntity )
			return true;
		return entity == null 
				|| entity instanceof CaveEntity
				|| entity instanceof WaterEntity
				|| entity instanceof LavaEntity;

	}

	/*
	 * getBlock get tile from map
	 */
	public BlankEntity getBlock(int x, int y) {
		if (x <= WorldMap.w && x >= 0 && y <= WorldMap.h && y >= 0)
			return worldMap[x][y];
		else
			return null;
	}

this.x and this.y are the position of the alien in world space.

Is there a better way to accomplish what I’m trying to achieve? Think slimes in Terraria.

Thanks