58fef08 · ifsrenderer-linux

ifsrenderer-linux commits / 58fef08

Stop replaying the same samples when the camera keeps moving

"if you go into flymode it moves around a bit doesn't hold its place."

The seed is constant and `dispatch_cnt` was reset to 0 by every invalidation. Both
feed the kernel's hash, so a restarted accumulation drew the IDENTICAL sample set
every time. Orbiting hides it - you stop, and it accumulates - but fly mode moves
continuously, so every frame invalidated and redrew the same sparse constellation
of points, which then slid across the screen with the camera. That is not the
fractal failing to hold its place; it is one fixed sample set being reprojected.

Split into two counters. `dispatch_count` is monotonic and feeds the RNG, so no
two dispatches ever share hash inputs. `since_reset` is zeroed by invalidate() and
only decides when to re-seed the point state. Continuous motion now shows fresh
noise that resolves when you stop, instead of a moving lattice.

`iterations` reports since_reset, which is what is actually on screen.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

58fef088c485db893ba832e6de9bc0cf8fbb7307

by plankatron <fleeky@gmail.com> · 2026-08-16T23:24:07.000Z

Changed files (1) +13 -4

blender/ifs_viewport.py +13 -4

…	…	@@ -139,7 +139,11 @@ class Session:
139	139	self.width = 0
140	140	self.height = 0
141	141	self.last_view = None
142		self.dispatch_count = 0
	142	# Two counters, deliberately. `dispatch_cnt` goes into the kernel's hash
	143	# and must NEVER repeat, or a restarted accumulation replays the identical
	144	# sample set. `since_reset` decides when to re-seed the point state.
	145	self.dispatch_count = 0 # monotonic, feeds the RNG
	146	self.since_reset = 0 # zeroed by invalidate()
143	147	self.frames = 0
144	148
145	149	self.kernel, self.drain, self.library = ifs_render._build_shaders(
…	…	@@ -297,7 +301,11 @@ class Session:
297	301	self.histogram.clear(format='UINT', value=(0, 0, 0, 0))
298	302	self.accum.clear(format='FLOAT', value=(0.0, 0.0, 0.0, 0.0))
299	303	self.state.clear(format='FLOAT', value=(0.0, 0.0, 0.0, 0.0))
300		self.dispatch_count = 0
	304	# dispatch_count is NOT reset: it is hash input, and rewinding it makes
	305	# every restart draw the same points. Under continuous camera motion that
	306	# is a fixed constellation sliding across the screen rather than the
	307	# fractal - which is what fly mode looked like.
	308	self.since_reset = 0
301	309
302	310	# -------------------------------------------------------------------- camera
303	311
…	…	@@ -369,7 +377,7 @@ class Session:
369	377	frame = gpu.types.GPUUniformBuf(ifs_host.pack_frame(
370	378	seed=0x9E3779B9, width=self.width, height=self.height,
371	379	dispatch_cnt=self.dispatch_count,
372		reset_points_state=1 if self.dispatch_count == 0 else 0,
	380	reset_points_state=1 if self.since_reset == 0 else 0,
373	381	invocation_iters=self.iters_per_frame))
374	382
375	383	self.kernel.bind()
…	…	@@ -382,6 +390,7 @@ class Session:
382	390	self.kernel.uniform_block(name, ubo)
383	391	gpu.compute.dispatch(self.kernel, ifs_render.WORKGROUPS, 1, 1)
384	392	self.dispatch_count += 1
	393	self.since_reset += 1
385	394
386	395	self.drain.bind()
387	396	self.drain.image('histogram_img', self.histogram)
…	…	@@ -420,7 +429,7 @@ class Session:
420	429
421	430	@property
422	431	def iterations(self):
423		return self.dispatch_count * self.iters_per_frame * ifs_render.INVOCATIONS
	432	return self.since_reset * self.iters_per_frame * ifs_render.INVOCATIONS
424	433
425	434
426	435	def start(document_path, iters_per_frame=400):