[I'm including the SFX list due to their being interested in this]
Hi Bruce, good info.
One question that popped up during Ed's presentation yesterday and the
following conversations was "what's a good WebGL toolkit". I believe you used
EWGL, right?
There seems to be quite a few webgl toolkits springing up, and I wondered if
you had any insight into which of them are worth considering and what are their
strengths and weaknesses.
-- Owen
On May 25, 2011, at 3:10 PM, Bruce Sherwood wrote:
> Here is an attempt to make it very easy to write WebGL programs:
>
> http://dl.dropbox.com/u/18859068/EasyWebGL20110525.zip
>
> Here is a summary found in the file oscillator.htm:
>
> // This is an attempt to emulate in JavaScript/WebGL
> // the ease of use found in Python/VPython/OpenGL (vpython.org).
> // In VPython, one writes simple programs that generate
> // navigable real-time 3D animations as a side-effect of
> // computations.
>
> // The following example uses vector operations only
> // sparingly compared to VPython, due to the absence of
> // operator overloading in JavaScript (e.g. vector1+vector2).
> // The example is intended as a simple proof of concept of
> // hiding all the extremely technical WebGL stuff, to make
> // it feasible for ordinary mortals to do 3D in a browser.
> // It is based on the well-known spinning box WebGL demo.
>
> // There's only one object (box) whose size is modifiable.
> // The color of everything is cyan, lighting is primitive.
> // There's some kind of timing glitch that is addressed by
> // the kludge of an alert box (in visual.js). You need to
> // acknowledge the alert, then on the next appearance you
> // need to check the box to show the alert no more. I would
> // appreciate advice on this problem: rendering is done but
> // doesn't appear until the end of the program, despite use
> // of gl.flush() and gl.finish().
>
> Bruce Sherwood
>
On May 25, 2011, at 8:08 PM, Bruce Sherwood wrote:
> Addendum: Here is the complete program in this easy WebGL environment.
> It's a numerical integration of two blocks (m1 and m2, each of mass m)
> connected by a spring (or rubber band, represented by a long box); the
> x component of momentum of the right-hand block is p.
>
> Hopefully much of the program is self-explanatory, but maybe not the
> rate(100) statement, which (taken from VPython) means "do no more than
> 100 iterations per second in this loop", to control the rate at which
> the animation proceeds. In VPython this statement is optional, because
> a rendering thread interrupts about 30 times per second to draw (using
> OpenGL) the objects with their current attributes. I don't know how to
> do that in JavaScript, so here the rate statement is obligatory,
> because it not only limits the loop iteration rate but also
> periodically drives the renderer.
>
> d = 1
> xi = 2
>
> m1 = box({pos:vector(-xi,0,0), size:[d,d,d]})
> m2 = box({pos:vector( xi,0,0), size:[d,d,d]})
> L = (m2.pos.x-d/2) - (m1.pos.x+d/2)
> w = 0.05*d
> V = L*w*w
> spring = box({pos:vector(0,0,0), size:[L,w,w]})
>
> L0 = .9*L
>
> ks = 10
> m = 1
> p = 0
> t = 0
> dt = .01
> while (t < 15) {
> rate(100)
> F = -ks*(m2.pos.x-L0/2)
> p += F*dt
> m2.pos.x += (p/m)*dt
> m1.pos.x -= (p/m)*dt
> L = (m2.pos.x-d/2) - (m1.pos.x+d/2)
> w = sqrt(V/L)
> spring.size = [L,w,w]
> t += dt
> }
>
> On Wed, May 25, 2011 at 3:10 PM, Bruce Sherwood
> <[email protected]> wrote:
>> Here is an attempt to make it very easy to write WebGL programs:
>>
>> http://dl.dropbox.com/u/18859068/EasyWebGL20110525.zip
>>
>> Here is a summary found in the file oscillator.htm:
>>
>> // This is an attempt to emulate in JavaScript/WebGL
>> // the ease of use found in Python/VPython/OpenGL (vpython.org).
>> // In VPython, one writes simple programs that generate
>> // navigable real-time 3D animations as a side-effect of
>> // computations.
>>
>> // The following example uses vector operations only
>> // sparingly compared to VPython, due to the absence of
>> // operator overloading in JavaScript (e.g. vector1+vector2).
>> // The example is intended as a simple proof of concept of
>> // hiding all the extremely technical WebGL stuff, to make
>> // it feasible for ordinary mortals to do 3D in a browser.
>> // It is based on the well-known spinning box WebGL demo.
>>
>> // There's only one object (box) whose size is modifiable.
>> // The color of everything is cyan, lighting is primitive.
>> // There's some kind of timing glitch that is addressed by
>> // the kludge of an alert box (in visual.js). You need to
>> // acknowledge the alert, then on the next appearance you
>> // need to check the box to show the alert no more. I would
>> // appreciate advice on this problem: rendering is done but
>> // doesn't appear until the end of the program, despite use
>> // of gl.flush() and gl.finish().
>>
>> Bruce Sherwood
>>
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