Sam Hocevar

12,037 reputation

22654

bio	website	sam.zoy.org
	location	Paris, France
	age	34
visits	member for	2 years, 2 months
	seen	23 hours ago
stats	profile views	917

I live in Paris, France.

I work on PlayStation, Xbox and computer games for a living. I write free software and all kind of crazy shit for fun. My interests: image processing, video coding, game development, maths, physics, compression, cryptography.

	12,037 reputation	bio	website	sam.zoy.org	visits	member for	2 years, 2 months
22654 badges		location	Paris, France		seen	23 hours ago

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Nov 2	revised	How can I rotate about an arbitrary point in 3D (instead of the origin)? correct a serious mistake in the calculations
Nov 2	revised	How can I rotate about an arbitrary point in 3D (instead of the origin)? add a summary
Nov 2	comment	How can I rotate about an arbitrary point in 3D (instead of the origin)? Seriously, could the people who upvote answers actually read them? I gave a method, an efficient formula, and even a demonstration. Yet the only upvoted answer, while providing some valuable information (and also some plainly wrong information), features none of these and does not even answer the question!
Nov 2	comment	How can I rotate about an arbitrary point in 3D (instead of the origin)? Sorry, but the matrix R is not a rotation matrix so it does not fit in the SQT system at all. You cannot "construct the rotation quaternion" that way. In fact the rotation quaternion does not change, it's the translation (and only the translation) that needs to be adapted.
Nov 2	revised	How can I rotate about an arbitrary point in 3D (instead of the origin)? more homogeneous computation
Nov 2	awarded	Analytical
Nov 2	revised	How to calculate vertex normals for a mesh in Java in OpenGL ES? fix spelling and layout
Nov 2	comment	How can I model the physics of an air blower? The amount of turbulence is more worrisome than the balls. Usually a velocity vector field is a good approximation in the case of steady flow (achieved with a very slow flow and/or very high viscosity). Some authors handle that problem by also computing a turbulence field, but that's more complicated to handle at runtime.
Nov 2	suggested	suggested edit on How to calculate vertex normals for a mesh in Java in OpenGL ES?
Nov 1	revised	How can I rotate about an arbitrary point in 3D (instead of the origin)? shorter answer
Nov 1	answered	How can I model the physics of an air blower?
Nov 1	revised	How can I rotate about an arbitrary point in 3D (instead of the origin)? minor tweaks
Nov 1	answered	How can I rotate about an arbitrary point in 3D (instead of the origin)?
Oct 27	answered	Interpolating from Current- to Target-value every frame
Oct 24	answered	How much extra power is required for a stereoscopic 3D game?
Oct 21	answered	XNA Rotation results in a pixelated image
Oct 21	awarded	Nice Question
Oct 21	comment	How does one avoid the “staircase effect” in pixel art motion? I don't think any decent oldschool game would have implemented a diagonal movement that has that staircase effect, because it would have looked like crap. Not looking like crap is a major part of the oldschool effect I wish to achieve :-)
Oct 21	answered	What technologies are required for 3D game development?
Oct 21	comment	How does one avoid the “staircase effect” in pixel art motion? +1 for pointing out an upper bound for v. Ilmari's suggestion is more detailed but you're providing useful information.