Editing Animation
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The question often comes up about how to make an animation in BRL-CAD. As BRL-CAD is primarily a solid modeling system for engineering and analysis purposes, there is (presently) only limited support for generating animations but it is possible with the assistance of some third-party tools. The basic method is to make your model, decide what keyframes and sequencing you want to have in your movie, render those keyframes as images, and then composite them into an animation. BRL-CAD can help will all but the last compositing step. | The question often comes up about how to make an animation in BRL-CAD. As BRL-CAD is primarily a solid modeling system for engineering and analysis purposes, there is (presently) only limited support for generating animations but it is possible with the assistance of some third-party tools. The basic method is to make your model, decide what keyframes and sequencing you want to have in your movie, render those keyframes as images, and then composite them into an animation. BRL-CAD can help will all but the last compositing step. | ||
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= Rendering image frames for an animation = | = Rendering image frames for an animation = | ||
− | There are a variety of rendering and image processing tools that support a wide range of visualization techniques. Tools that may be of interest include ''' | + | There are a variety of rendering and image processing tools that support a wide range of visualization techniques. Tools that may be of interest include '''rt''', '''rtedge''', '''rtxray''', '''pixmatte''', and '''pixblend''' as well as a variety of other rendering and image processing tools. |
− | If the animation you want is very simple like having an animation of something spinning, the relatively simple process is described in the [[#Fly-around animation]] section. If, however, what you want to animate is considerably more complex, there are a variety of tools that become important for setting up animation paths, managing keyframes, interpolating between frames, and previewing the animation. There are animation tools in MGED (see the '''animmate'' command | + | If the animation you want is very simple like having an animation of something spinning, the relatively simple process is described in the [[#Fly-around animation]] section. If, however, what you want to animate is considerably more complex, there are a variety of tools that become important for setting up animation paths, managing keyframes, interpolating between frames, and previewing the animation. There are animation tools in MGED (see the '''animmate''' command for starters) as well as a variety of animation table processing tools outside of MGED. |
== Detailed arbitrary path animation == | == Detailed arbitrary path animation == | ||
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#!/bin/sh | #!/bin/sh | ||
for i in `loop 000 359 10` ; do | for i in `loop 000 359 10` ; do | ||
− | rt -a $i -e 35 -w 640 -n 480 -o image$i. | + | rt -a $i -e 35 -w 640 -n 480 -o image$i.pix database.g top_level_object |
+ | pix-png -w 640 -n 480 image$i.pix > image$i.png | ||
+ | rm -f image$i.pix | ||
done | done | ||
− | This renders 36 images of the object top_level_object from a geometry database that was named '''database.g''', creating images every 10 degrees (azimuth) at an elevation of 35 degrees. The images are named ''image000. | + | This renders 36 images of the object top_level_object from a geometry database that was named '''database.g''', creating images every 10 degrees (azimuth) at an elevation of 35 degrees. The images are named ''image000.pix'' through ''image350.pix''. |
Walking through the shell script, the second line '''''(for i in `loop 000 359 10` ; do)''''' just sets up a loop to run with variable '''i''' set to the next number each pass through the for loop. You can see the expansion by running the loop command directly: | Walking through the shell script, the second line '''''(for i in `loop 000 359 10` ; do)''''' just sets up a loop to run with variable '''i''' set to the next number each pass through the for loop. You can see the expansion by running the loop command directly: | ||
− | [sean@bz (Fri Feb 13 11:23:07) ~]$ loop 000 | + | [sean@bz (Fri Feb 13 11:23:07) ~]$ loop 000 259 10 |
000 | 000 | ||
010 | 010 | ||
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350 | 350 | ||
− | The third line calls '''rt''' to render an image. The '''-a''' option sets the azimuth value and the '''-e''' option sets the elevation value. The '''-w''' and '''-n''' options set the width and height of the image respectively. The '''-o''' option specifies the filename for the output image that is generated. Finally, there is the name of the database to read from and the name of the object in that database that we want to render. The object is automatically centered in the view. | + | The third line calls '''rt''' to render an image. The '''-a''' option sets the azimuth value and the '''-e''' option sets the elevation value. The '''-w''' and '''-n''' options set the width and height of the image respectively. The '''-o''' option specifies the filename for the output image that is generated. Finally, there is the name of the database to read from and the name of the object in that database that we want to render. The object is automatically centered in the view. |
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+ | The fourth line converts the .pix file to a .png file. This is often useful/necessary because .pix files are raw first quadrant image files that aren't as prevalently supported as the PNG file format. | ||
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+ | The fifth line deletes the pix file (since we have the png file now anyway). | ||
= Compositing an animation = | = Compositing an animation = | ||
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== With ffmpeg == | == With ffmpeg == | ||
− | + | To be written. | |
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== With Photoshop == | == With Photoshop == | ||
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== With Mencoder == | == With Mencoder == | ||
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mencoder mf://*.png -mf w=800:h=600:fps=25:type=png -ovc lavc -lavcopts vcodec=mpeg4:mbd=2:trell -oac copy -o movie.avi | mencoder mf://*.png -mf w=800:h=600:fps=25:type=png -ovc lavc -lavcopts vcodec=mpeg4:mbd=2:trell -oac copy -o movie.avi | ||
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then you get a smooth animation of your geometry. | then you get a smooth animation of your geometry. | ||
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