• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
XsoodX

Object Collision Problem

3 posts in this topic

I am trying to make a simple physics based game in SDL, and i require a ball to bounce of lines in game.

 

However, when the ball collides with the line, it clips through it, messing up the collision count.

The problem is due to the speed of the ball. If the ball travels fast enough, it can pass right through the line.

I use frame independent motion and a circular collision detection for the ball

 

How can i make sure the collision doesn't clip?

 

Code For the Ball Collision Detection

bool Projectile::check_collision(Line L)
{
	int X1,X2,Y1,Y2,CL;
	int Cx=0,Cy=0,CP=0,Px=0,Py=0;
	float shortest_distance;
	double slopeL=0,slopeP=0;

	L.get_Line(X1,Y1,X2,Y2);
	getLocation(Px,Py);
	Px+=size/2;
	Py+=size/2;

	if(X2-X1!=0)
	{
		slopeL=(Y2-Y1)/(X2-X1);
		slopeP=-1/slopeL;
		//Y=mX+C;
		CL=Y1-slopeL*X1;
		CP=Py-slopeP*Px;
		Cx=(CL-CP)/(slopeP-slopeL);
		Cy=slopeP*Cx + CP;
	}
	else 
	{
		Cy=Py;
		if(X2>Px)
		Cx=X2-Px;
		else
		Cx=Px-X2;
	}

	shortest_distance=sqrt(pow(double(Cx-Px),2)+pow(double(Cy-Py),2));	

	if(shortest_distance<size/2)
	{
		if(X2-X1!=0)
		on_collision(slopeL);
		else
		on_collision();
		return true;
	}
	else
		return false;

}

If any more info is needed please tell me.

0

Share this post


Link to post
Share on other sites

for such simple game you could:

divide circle step by 10

and do 10 circle moves and collision checks per loop.

1

Share this post


Link to post
Share on other sites

A potential solution is to "sweep out" a box (or capsule if the ends are rounded to fit the circle) that describes the motion of the circle over the whole timestep and then to do collision detection with the swept out box (or capsule). The picture below shows a swept out box.

 

[attachment=18239:Problem.png]

 

[attachment=18240:Solution.png]

2

Share this post


Link to post
Share on other sites

A potential solution is to "sweep out" a box (or capsule if the ends are rounded to fit the circle) that describes the motion of the circle over the whole timestep and then to do collision detection with the swept out box (or capsule). The picture below shows a swept out box.

 

attachicon.gifProblem.png

 

attachicon.gifSolution.png

I did something like this in the past, and then put it to intercepted and moved the ball to the halfway position and set the velocities so that on the next time step it would be right... if your total velocity drops too low though, you may have to adjust where you move it to. My speed stayed the same for the whole problem, so moving it halfway worked great. You could do a deterioration to find out exactly where to move it if you needed to. (For instance, if losing 50% of velocity, would probably want to move back to 25% along the way of the box before adjusting velocity).

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0