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Re: [Public WebGL] rendering to "texture1D" (Chrome bug?)



FYI: the half-pixel difference is compensated in ANGLE I think.

On Tue, Jan 11, 2011 at 7:28 AM, Steve Baker <steve@sjbaker.org> wrote:
>
> Drawing a 1 pixel wide line in a 1 pixel wide image sounds like you
> might be having problems with it being cut off at the edge or
> something.  You'd get away with it on OpenGL renderers where the line
> width can be >1 but under ANGLE (aka Direct3D) there is no line width
> control...also Direct3D has a half-pixel coordinate shift relative to
> OpenGL in some situations - which could also account for the difference.
>
> Lines are a bit tricky.  I would try drawing a quadrilateral that's
> definitely wider than the viewport.
>
>  -- Steve
>
> On 01/11/2011 03:11 AM, Evgeny Demidov wrote:
>>
>> For N-bodies simulations (N~256) I'd like to store N 3D coordinates in
>> Nx1 textures_2D (RGB float later). In a simple test (no extensions)
>> http://www.ibiblio.org/e-notes/webgl/test/tex1D.html
>> I set gl.viewport(0, 0, n, 1);  and try to render white (-1,0,0,
>> 1,0,0) line on black background. Unfortunately in Chromium with OpenGL
>> drivers (under Windows XP + ATI) I see the black background. I get
>> white page in Firefox and Chrome with ANGLE.
>> 1. is it a bug?
>> 2. how shall I render to "1D" textures? (I'll try to draw 2x2 square
>> meanwhile)
>>
>> Evgeny
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