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2023-09-07modules/flow: add TODO blurb abot per-cpu seedsVito Caputo
Writing this down so it doesn't completely fall off my radar.
2023-09-06modules/flow: fix elements overflow bugVito Caputo
s->count isn't always perfectly divisable by n_cpus, which is why ctxt->n_elements is computed from n_cpus * elements_per_cpu in the transition to threaded rendering for flow. That's all fine and dandy, but the ctxt->elements initialization loop was still using the vestigial s->count from the pre-threaded implementation. So on core counts where ctxt->n_elements was smaller than s->count, initialization scribbled. Thanks Sketch for assistance in chasing this down w/ASAN enabled on a box that exhibited crashing w/rtv,channels=flow.
2023-09-05modules/flow: fix default countVito Caputo
57bae7 removed the default from the settings list when bumping the counts, oops!
2023-09-05modules/flow: add "(threaded)" labelVito Caputo
The convention has been to label threaded modules in their description.
2023-09-05modules/flow: bump the counts up a bitVito Caputo
Now that there's threaded rendering, handling larger counts without bogging down the frame rate on anything remotely modern is feasible.
2023-09-04modules/flow: restore previous Z depthVito Caputo
While optimizing the threaded rendering in commit 6d6c141, the pos.{xy} expanding from 0-1 to -1..+1 were eliminated from the inner loops in favor of just having the positions always in -1..+1 coordinates. But I missed that it was only the x/y coordinates which were being expanded, with .z being left in the 0-1 space, which had a desirable aesthetic effect of condensing the Z space, flattening everything. This commit undoes that, without reintroducing the expansion to the inner loops. It's a bit crufty because now .z is treated exceptionally throughout as 0..1 while {.x,.y} are in -1..+1, but it's fine for now.
2023-09-04modules/flow: implement threaded renderingVito Caputo
This exploits the just added multipass rendering support. In the first pass, the flow-field is sampled and applied to the elements, with every thread operating on its own subset of the elements list. Since the flow-field sampling is all read-only, it's perfectly safe too do in parallel. Nothing is drawn in the first pass, it's only the elements updating according to the flow-field which is performed. In the second pass, the elements are rendered in parallel using the slice_per_cpu fragmenter. Since the elements are kept on a simple array, with no spatial indexing, every thread must visit every element. Since the fragmenter used divides the frame into horizontal slices, every thread needing to reject elements not overlapping its region can take some shortcuts in easily identifying elements entirely outside its region. But the whole 3d->2d projection step must still be performed for every element's current position and +n_iters final position for the frame, which does have a divide unfortunately. Nonetheless, this change improves frame rates substantially on my 2c/4t i7 X230 as benchmarked w/--video=mem,1366x768: --seed=0x64fa9508 '--module=rtv,channels=flow,duration=3,context_duration=3,caption_duration=0,log_channels=on,snow_duration=0,snow_module=none' '--video=mem,size=1366x768' rtv channel settings: 'flow,size=4,count=40000,speed=.8' FPS: 261 FPS: 265 rtv channel settings: 'flow,size=4,count=1000,speed=.9' FPS: 1153 FPS: 3204 FPS: 2934 rtv channel settings: 'flow,size=8,count=5000,speed=.9' FPS: 2923 FPS: 1634 FPS: 1592 rtv channel settings: 'flow,size=2,count=50000,speed=.4' FPS: 1006 FPS: 219 FPS: 268 rtv channel settings: 'flow,size=16,count=30000,speed=.8' FPS: 304 FPS: 350 FPS: 343 rtv channel settings: 'flow,size=16,count=30000,speed=.02' FPS: 379 FPS: 503 FPS: 472 rtv channel settings: 'flow,size=8,count=1000,speed=.16' FPS: 1393 FPS: 3822 FPS: 3876 --- Prior to this commit: --seed=0x64fa9508 '--module=rtv,channels=flow,duration=3,context_duration=3,caption_duration=0,log_channels=on,snow_duration=0,snow_module=none' '--video=mem,size=1366x768' rtv channel settings: 'flow,size=4,count=40000,speed=.8' FPS: 53 FPS: 53 rtv channel settings: 'flow,size=4,count=1000,speed=.9' FPS: 426 FPS: 1366 FPS: 1335 rtv channel settings: 'flow,size=8,count=5000,speed=.9' FPS: 1097 FPS: 368 FPS: 367 rtv channel settings: 'flow,size=2,count=50000,speed=.4' FPS: 279 FPS: 73 FPS: 74 rtv channel settings: 'flow,size=16,count=30000,speed=.8' FPS: 71 FPS: 71 FPS: 70 rtv channel settings: 'flow,size=16,count=30000,speed=.02' FPS: 136 FPS: 305 FPS: 305 rtv channel settings: 'flow,size=8,count=1000,speed=.16' FPS: 972 FPS: 2593 FPS: 2634
2023-09-03modules/flow: expose speed as a tapVito Caputo
Nothing too crazy here, the speed= setting still controls the speed in lieu of something driving the tap.
2023-09-03modules/flow: don't reap elements on screen-space exitVito Caputo
This is too aggressive and produces some undesirable visible artifacts on the periphery, especially for slow-moving small-size fields. In such scenarios the elements near the edges would be excessively pruned when the direction wandered off-screen, then leaving an overly sparse region when the direction inevitably wandered back. This is still an issue but it's far less prominent when only clipping to the flow field boundaries... since the FOV doesn't quite encompass the edges of the flow field. Now the elements can survive wandering a bit off-screen, and re-enter.
2023-09-03modules/flow: add colorsVito Caputo
This is a first stab at colorizing the output. The flow field now has two v3f_t datums per cell, direction and color. It's a bit pastel-y and color choice/palettes definitely needs work, at least some gamma correction would make sense. But I kind of like the pastel look actually, some of the combinations start looking very 80s aesthetic. A good way to watch flow's possibilities is: --module=rtv,channels=flow,duration=10,context_duration=10,caption_duration=0 \ --video=sdl,fullscreen=on --defaults --go The long-ish duration really gives a chance to get into the groove of things before switching
2023-09-02modules/flow: minor cleanup of ff_new()/ff_free()Vito Caputo
Simplify ff_new() failure path by using ff_free(), also make ff_free() more ergonomic by returning NULL.
2023-09-02flow: implement a 3D flow field moduleVito Caputo
This is kind of a particle system, where the particles are pushed around through a 3D vector space treated as a flow field. No physics are being simulated here, it's just treating the flow field as direction vectors that are trilinearly interpolated when sampled to produce a single direction vector. That direction vector gets applied to particles near it. To keep things interesting the flow field evolves by having two distinct flow fields which the simulation progressively alternates sampling from. For every frame, both flow fields are sampled for every particle, but how much weight is given to the influence of one vs. the other varies by a triangle wave over time. When the weight is biased enough to one of the flow fields near a peak/valley in the triangle wave, the other gets re-populated while its influence is negligible, also interpolating its new values with 25% influence from the active field. The current flow field population routine is completely random. Yet there's a surprising amount of emergent order despite being totally randomized direction vectors. Currently supported settings include: size= the width of the 3D flow field cube in direction vectors (the number of vectors is size*size*size) count= the number of particles/elements speed= how far a particle is moved along the current sample's direction vector This was first implemented in 2017, but sat unfinished in a topic branch for myriad reasons. Now that rototiller has much more robust settings infrastructure, among other things, it seemed worth finishing this up and merging.
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