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      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.
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amerigo14

Ray collision help?

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Hi I'm creating a game using OpenGL and c++ for my final year project and I've got a quick question about using rays for collisions. I understand the theory behind it but I'm having an issue implementing it. I'm loading my models using Assimp and I'm trying to create a bounding box around the models so that I can check for a ray-box intersection, but when the transformations are applied during rendering, the box does not move with the model. I have created my own vertex and fragment shaders that draws the models. What approach is best for situation? Should I find a way to also move the bounding box, or is there another method to help with this? I considered using a frame buffer object from the point of view of the ray but I think this is overcomplicating things. I'm using rays as the game is a first person sniping game, and bullets would move too fast to find the box intersections.
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First choose whether you want to use axis-aligned bounding boxes ([url="http://clb.demon.fi/MathGeoLib/docs/AABB_summary.php"]AABB[/url]), or oriented bounding boxes ([url="http://clb.demon.fi/MathGeoLib/docs/OBB_summary.php"]OBB[/url]).

To generate the optimal minimum AABB for a model, see [url="http://clb.demon.fi/MathGeoLib/docs/AABB_SetFrom.php"]AABB::SetFrom(pointArray);[/url]
To generate the optimal minimum OBB for a model, google for the "Rotating Calipers" method.
To intersect a ray against an AABB, see [url="http://clb.demon.fi/MathGeoLib/docs/AABB_IntersectRayAABB.php"]AABB::IntersectRayAABB[/url].
To intersect a ray against an OBB, see [url="http://clb.demon.fi/MathGeoLib/docs/OBB_Intersects.php"]OBB::Intersects(Ray)[/url].

To perform the ray-box intersection test, update the box and ray coordinates into same coordinate space (i.e. world space, or object's local space) for the test. This means that you update your box representation along with the transform of your object to avoid "the box does not move with the model" issue you described.

Trying to go the route of rendering the object into a frame buffer and doing per-pixel tests to check for intersection is a poor idea due to added latency and performance costs.
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Thanks for the information! I will attempt to implement this, I figured as much with the frame buffer.
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Hi I tried to implement the AABB bounding box, but when I apply the model's transformation matrix the values are incorrect. I think this is something to do with the rotation in th matrix. After debugging i found a lot of the values were low numbers. To apply the transformations I set each corner of the box and applied the transformation to each one, then circled between them to find the lowest value.
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