Animated gifs are old and inefficient, but in some places it’s the only format you can upload.
It’s easy to use the ffmpeg video writer from OPENRNDR to produce such files. Here a template:
Imports
import org.openrndr.application
import org.openrndr.draw.isolatedWithTarget
import org.openrndr.draw.renderTarget
import org.openrndr.ffmpeg.VideoWriter
import org.openrndr.ffmpeg.VideoWriterProfile
import java.lang.Math.toDegrees
import kotlin.math.PI
fun main() = application {
configure {
width = 512
height = 512
}
program {
val videoWriter = VideoWriter.create().apply {
size(width, height)
profile(GIFProfile())
output("/tmp/my_anim.gif")
start()
}
val videoTarget = renderTarget(width, height) {
colorBuffer()
depthBuffer()
}
val totalFrames = 120
extend {
val norm = (frameCount % totalFrames) / totalFrames.toDouble() // cycles 0.0 .. 1.0
val radians = 2 * PI * norm // cycles 0.0 .. TWO_PI
val angle = toDegrees(radians) // cycles 0.0 .. 360.0
drawer.isolatedWithTarget(videoTarget) {
// Draw stuff here.
// You can use one of the three variables above
// to produce looping animations.
}
videoWriter.frame(videoTarget.colorBuffer(0))
drawer.image(videoTarget.colorBuffer(0))
if (frameCount == totalFrames) {
videoWriter.stop()
application.exit()
}
}
}
}
class GIFProfile : VideoWriterProfile() {
override fun arguments(): Array<String> {
return arrayOf("-vf", "split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse=dither=none:diff_mode=rectangle")
}
}
The simple GIFProfile optimizes the colors and disables the dithering. With dithering I was getting very heavy files. Once the file is exported, I run this command to optimize the file further:
gifsicle --loop --delay=2 --colors 16 --optimize=2 my_anim.gif >my_anim_optimized.gif
Delay 2 gives about 60 fps I think. I try to reduce the colors as much as possible, depending on what I’m drawing. You can read more about gifsicle.
Do you have any tricks to make gif loops?
