• 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
Amnesty2

Zooming about to a point (2D surface)

2 posts in this topic

Tiger.jpg

 

 

Hello, I need some help with this math. I've been at this for hours now.

 

I have a large surface (the whole tiger) and a view in blue that is 700,400. Right now, i have it zooming and panning with bounds checking fine, but can't figure out how to zoom to the mouse cursor (red dots).

 

Say, im at 660, 300 local coordinates of view A and zoom in, how do I get what appears in view B? Currently, it just zooms into 0,0 and would get a close up of the ear instead. Basically, I want the functionality of Paint, or Paint.NET or any image editor.

This is all 2D math btw

 

    // x, and y are local coordinates
    void Canvas::setScale(float s, int x, int y) 
    {
        // m_x and m_y are are coordinates into the full canvas
        // the view treats them as 0,0
        // in view marked A, these would something like 200,100 and would be at the tip of the ear
        // after this function i want them to point right above the eye like in the view B example

        float oldscale = m_scale;
        m_scale = s;

        // TODO add the math 

        CheckBounds();
    }

 

Right now, i have some math filled in but it only kinda working.. Its more of a hack and is definately not fluid or percise.
I know there most be a standard way of doing this.
 
 
Thanks
 
0

Share this post


Link to post
Share on other sites
First figure out the location of the red dot in full-canvas coordinates.  I'll call that z:
 
z_x = m_x + x/s
z_y = m_y + y/s
 
That assumes that s increases as the zoom gets bigger, so that s = 2 for 2x zoom.  Now use z to find the location of the upper-left corner in full-canvas coordinates:
 
m_x = z_x - 0.5*viewSize_x/s
m_y = z_y - 0.5*viewSize_y/s
 
Putting those together:
 
m_x = m_x + x/s - 0.5*viewSize_x/s
m_y = m_y + y/s - 0.5*viewSize_y/s
 
Of course, if it makes you happy you can make a very slight optimization by factoring out the 1/s.  If I'm understanding your code correctly, that should do what you want - though, as a disclaimer, it's way too late in the morning for me to test it out myself. 
1

Share this post


Link to post
Share on other sites

Works Great! thanks

 

In addition to your formulas, I averaged the new m_x and m_y values with the old ones so they were not changed so drastically. Seems really smooth now.

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