Subject:
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Re: Some secrets of MLCad revealed ...
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Newsgroups:
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lugnet.cad.mlcad
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Date:
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Wed, 9 Jul 2003 13:16:38 GMT
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Viewed:
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3686 times
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In lugnet.cad.mlcad, Michael Lachmann wrote:
> Ok since a lot of you are asking me to provide more details about MLCad's
> rendering technic I'll go and tell you some details about it:
>
> 3) Image buffering
> This once reduced drawing most but doesn't work for perspective display.
> MLCad is using the scanline conversion and z-buffering methode for drawing.
> Now imagine a stud drawn several thousend times and each time you calculate
> the scan lines and depths of the single points.
> Image buffering now is drawing the part into a virtual buffer first, and
> then using this virtual buffer to actually draw the image. Now you do not
> have to do all the calculations again, but can use precalculated information
> instead. When drawing the buffer MLCad checks the actual depth of the stud
> drawn and adds the z-buffer information for every single pixle to this
> depth. The further processing is the same, if the pixel is in front of the
> last pixel drawn, it will be drawn, otherwice not.
> The image buffer itself is only reset if the orientation of part is changed.
> This algorythm is used depending on the user setting even for complete
> bricks. This means MLCad no longer has to calculate every single point,
> line, triangle .. for the same part as long as it's orientation remains the
> same.
I'm a bit behind on this thread, but thanks Michael. That explains
a lot. I never thought of the image buffering approach for orthographic
displays. It's a really neat idea! I do have a question though. How
do you handle colors in the image buffers? I guess the image buffers
don't go with the cached parts, but with a colored instance of the part?
Or do you add the color when you adjust to the final Z values?
I can imagine using precalculated images would do wonders for rendering
all the studs in an orthographic projection. Have you thought about
using Lars' bounding box occlusion test for eliminating needless stud
drawing in pespective renderings?
Thanks,
Don
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Message has 1 Reply:
 | | Re: Some secrets of MLCad revealed ...
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| Hi Don, "Don Heyse" schrieb im Newsbeitrag news:HHrE7q.1vCq@lugnet.com... (...) The image buffers, just keep the light information in it, but not the color itself, the color is assigned during pasting the image onto the screen. I think I haven't (...) (21 years ago, 9-Jul-03, to lugnet.cad.mlcad)
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Message is in Reply To:
| | Some secrets of MLCad revealed ...
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| Ok since a lot of you are asking me to provide more details about MLCad's rendering technic I'll go and tell you some details about it: During the development of MLCad I went through several stages trying to make rendering faster, some of them with (...) (21 years ago, 4-Jul-03, to lugnet.cad.mlcad)
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