• 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
Caglow

Drawing a Sphere around the "Camera"

4 posts in this topic

First of all, I'm new here (and to OpenGL/GLUT for that matter) so if there's something that seems extremely obvious, sorry. Anyways, I'm trying to draw a sphere with the center lying on the camera. I've managed to draw the sphere for now...and need something to move the camera into the middle. I'm quite sure a sphere is hollow. If it isn't, then I need to get it to be. This is for a planetarium program which I'm converting from GDI+ to OpenGL.
0

Share this post


Link to post
Share on other sites
Where is it if it's not in the center of the world? Check the part where you call glMatrixMode(GL_MODELVIEW);

Every matrix transformation done after that modify the position of the object. You can either have some combined basic transformations (glRotatef, glTranslatef) or use gluLookAt which is acting as a "camera".

If you want to draw your sphere right at the middle of the camera, just don't do any transformation at all. Right after you set the GL_MODELVIEW matrix mode, call glLoadIdentity() and remove every other transformation you can find. Then draw your sphere, and it should appear at world pos (0,0,0), in your face.

Of course, your sphere model is probably made so the normals point from the exterior faces, so if you want to see the inside you will have to change the culling mode with glCullFace().
0

Share this post


Link to post
Share on other sites
Yes it's hollow, as with everything it's made up from infinitely thin polygons.
It's also pretty simple to do, just call glLoadIdentity(); to reset the matrix.
This will render the sphere at coordinates 0,0,0, then to make it visible you have to make sure the spheres radius is larger than the nearplane and smaller than the farplane, then you need to call glFrontFace(GL_CW); to view the backside of the polygons (you have to reset that state later with GL_CCW).
0

Share this post


Link to post
Share on other sites
If you just set the MODELVIEW matrix to identity you'll get the "inside" of the sphere drawn as has been said already, but you won't be able to rotate the view to look around the sphere. I'd imagine that would completely defeat the purpose ;)

Try the following instead:

- Push Matrix
- Load Identity
- Apply the view matrix
- Translate to the camera's position
- Render Sphere (inside out)
- Pop matrix

So, what you're doing is building up a MODELVIEW matrix with the translated exactly over the camera, and rendering that. This way, if you rotate the camera, you'll around inside of the sphere.

If you know the camera's rotation then you can replace the 3rd and 4th steps with a glRotate, and you'll have the same effect.

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