Subscribe to GameDev.net Direct to receive the latest updates and exclusive content.
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.
Posted 27 October 2012 - 01:45 PM
Posted 27 October 2012 - 02:28 PM
Posted 27 October 2012 - 02:59 PM
Posted 27 October 2012 - 03:16 PM
That'd be an interesting bunch of code, regardless of the language they were written in. Do you them up on a website somewhere where I could peruse them?When I started programming at age eight on a 68000-based Mac, I was fascinated by QuickDraw's ability to draw geometric shapes so quickly. This led to years of searching as to how (I started well before the internet was established). I now have an admittedly pointless, but interesting cache of pixel-perfect (midpoint) geometric object drawing code (ellipses, elliptical arcs, lines, etc.). This kind of became a hobby of mine.
Posted 27 October 2012 - 03:22 PM
That'd be an interesting bunch of code, regardless of the language they were written in. Do you them up on a website somewhere where I could peruse them?
Posted 27 October 2012 - 04:08 PM
I understand that I can subdivide the curve down so that I am drawing single pixel lines, but that is again drawing lines. What I am looking for is Bezier curve code that draws a Bezier similarly to Bresenham's line drawing code. In other words, the initial pixel is calculated and the rest are incrementally derived from some function. The curve would be plotted pixel by pixel by pixel.
My interest in this is really just personal. I have no need for it, but it always bothered me that I could not find any examples. I am just really curious if this has ever been done, and if so, I would like to see the code.
Posted 28 October 2012 - 06:04 AM
Posted 28 October 2012 - 09:57 AM
All midpoint algorithms describe the curves with an equation in the form f(x, y) = 0 (with integer or rational* coefficients).
Posted 28 October 2012 - 11:21 AM
We examine a class of algorithms for rasterizing algebraic curves based on an implicit form that can be evaluated cheaply in integer arithmetic using finite differences. These algorithms run fast and produce “optimal” digital output, where previously known algorithms have had serious limitations. We extend previous work on conic sections to the cubic and higher order curves, and we solve an important undersampling problem.
Posted 31 October 2012 - 08:42 AM
Posted 31 October 2012 - 11:35 AM
Posted 31 October 2012 - 04:33 PM
That remains quite complex though. For one, for cubic beziers it's much much easier to recursively split them into quadratic beziers than analyzing them to find out whether they're looping or whatnot to be able to rasterize them like in the paper. Quadratics are so much easier to work with, and approximating a cubic bezier with one or more quadratic is rather easy and doesn't really even result in any noticeable curvature error even when zooming in (while keeping the advantage of pixel perfect curve rendering at any zoom level).Windows 7 performs font rasterization using the GPU directly
This does exactly what you want - which is drawing triangles and shading each pixel according to an implicit equation that derives from a Bezier curve
No slow and messy subdividing and drawing lines etc.
You can get a detailed description of how they do it in "Rendering Vector Art on the GPU" by Charles Loop and Jim Blinn
This is free online: http://http.develope...gems3_ch25.html
Edited by Zlodo, 31 October 2012 - 04:38 PM.
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.
GameDev.net™, the GameDev.net logo, and GDNet™ are trademarks of GameDev.net, LLC.