Gauges, guidelines and onionskins

Anything related to a beta release of JPatch: Bugs, enhancements, general discussion...

Gauges, guidelines and onionskins

Postby dcuny » Sat Jul 16, 2005 11:08 pm

In the ancient (pre-computer) days of 3D animation, people used guides to keep track of where a puppet had been in a prior pose:

Image

With the advent of digital video, this has been pretty much replaced by onionskinning, with the ability to overlay the prior frame with the current frame:

Image

Most computer animation programs support onionskinning:

Image

In Animation:Master, you can set horizontal and vertical guides. They disappear if you aren't perpendicular to the axis they were set on:

Image

Lacking that, you can always place small generic "marker" objects in your scene to keep track of an object's movement from frame to frame:

Image

It would be very helpful if JPatch supported something like this. The simplest would be A:M style horizontal and vertical guides.
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Postby sascha » Sun Jul 17, 2005 8:26 am

Thanks David, that's pretty interesting!

About onionsklinning: A simple way would be to draw the last frame in wireframe and the current frame in shaded mode. Averaging two (or more) frames should be possible with OpenGL offscreen p-buffers, but I think these are extensions and not supported on all cards :?

Markers should be easy too. I'm afraid I don't understand the line guides though. Does it make sense to constrain the to be parallel to one of the major axis, or can the by any line in 3D space? Why do they disappear?



My GL vieport class is quite functional - it can draw shaded triangles, lines, images and text, everything JPatch needs. I'll add prespective projection to my software renderer so that it has the same features as the GL viewport, so the user will be able to switch between Java2D, the software (zbuffer) renderer and OpenGL.

I've started reworking the tools to work on a more abstract representation than controlpoints (so it will be possible to use the same tools to modify bones or, for example, vetices of poly-models as well).Looks quite promising so far, but I need some minor modifications for the tools to work with perspective viewports as well, so I decided to finish that perspective and OpenGL viewports first.
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Postby dcuny » Sun Jul 17, 2005 9:07 am

Sascha wrote:About onionsklinning: A simple way would be to draw the last frame in wireframe and the current frame in shaded mode.
Or you might just draw only the bones, since that's generally what you want to match up to. Some programs give the option of having multiple objects.

You can check out the Animanium demo; it's got onionskinning.

Markers should be easy too.
The example (from AoI) used plain objects. I think they were set to be invisible so they wouldn't render. If you did something similar, you could simply not export the objects...

I'm afraid I don't understand the line guides though. Does it make sense to constrain the to be parallel to one of the major axis, or can the by any line in 3D space?
I don't know; I haven't really played with them - I've only really seen them on the A:M demo video (Exercise 4 - " "It's A Pitch").

Why do they disappear?
I'm only guessing about that part. :)

Since the lines are only set in two dimensions, what value do they have for the third axis? (I could be wrong about this, though.) I could try firing up my A:M demo and looking.

My GL vieport class is quite functional - it can draw shaded triangles, lines, images and text, everything JPatch needs.
Groovy!

I've started reworking the tools to work on a more abstract representation than controlpoints (so it will be possible to use the same tools to modify bones or, for example, vetices of poly-models as well).Looks quite promising so far, but I need some minor modifications for the tools to work with perspective viewports as well, so I decided to finish that perspective and OpenGL viewports first.
I can wait. :)
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