Sync all skills and memories 2026-04-14 07:27

skills/creative/manim-video/references/troubleshooting.md

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+# Troubleshooting
+
+## LaTeX Errors
+
+**Missing raw string** (the #1 error):
+```python
+# WRONG: MathTex("\\frac{1}{2}")  -- \\f is form-feed
+# RIGHT: MathTex(r"\frac{1}{2}")
+```
+
+**Unbalanced braces**: `MathTex(r"\frac{1}{2")` -- missing closing brace.
+
+**LaTeX not installed**: `which pdflatex` -- install texlive-full or mactex.
+
+**Missing package**: Add to preamble:
+```python
+tex_template = TexTemplate()
+tex_template.add_to_preamble(r"\usepackage{mathrsfs}")
+MathTex(r"\mathscr{L}", tex_template=tex_template)
+```
+
+## VGroup TypeError
+
+**Error:** `TypeError: Only values of type VMobject can be added as submobjects of VGroup`
+
+**Cause:** `Text()` objects are `Mobject`, not `VMobject`. Mixing `Text` with shapes in a `VGroup` fails on Manim CE v0.20+.
+
+```python
+# WRONG: Text is not a VMobject
+group = VGroup(circle, Text("Label"))
+
+# RIGHT: use Group for mixed types
+group = Group(circle, Text("Label"))
+
+# RIGHT: VGroup is fine for shapes-only
+shapes = VGroup(circle, square, arrow)
+
+# RIGHT: MathTex IS a VMobject — VGroup works
+equations = VGroup(MathTex(r"a"), MathTex(r"b"))
+```
+
+**Rule:** If the group contains any `Text()`, use `Group`. If it's all shapes or all `MathTex`, `VGroup` is fine.
+
+**FadeOut everything:** Always use `Group(*self.mobjects)`, not `VGroup(*self.mobjects)`:
+```python
+self.play(FadeOut(Group(*self.mobjects)))  # safe for mixed types
+```
+
+## Group save_state() / restore() Not Supported
+
+**Error:** `NotImplementedError: Please override in a child class.`
+
+**Cause:** `Group.save_state()` and `Group.restore()` are not implemented in Manim CE v0.20+. Only `VGroup` and individual `Mobject` subclasses support save/restore.
+
+```python
+# WRONG: Group doesn't support save_state
+group = Group(circle, Text("label"))
+group.save_state()  # NotImplementedError!
+
+# RIGHT: use FadeIn with shift/scale instead of save_state/restore
+self.play(FadeIn(group, shift=UP * 0.3, scale=0.8))
+
+# RIGHT: or save/restore on individual VMobjects
+circle.save_state()
+self.play(circle.animate.shift(RIGHT))
+self.play(Restore(circle))
+```
+
+## letter_spacing Is Not a Valid Parameter
+
+**Error:** `TypeError: Mobject.__init__() got an unexpected keyword argument 'letter_spacing'`
+
+**Cause:** `Text()` does not accept `letter_spacing`. Manim uses Pango for text rendering and does not expose kerning controls on `Text()`.
+
+```python
+# WRONG
+Text("HERMES", letter_spacing=6)
+
+# RIGHT: use MarkupText with Pango attributes for spacing control
+MarkupText('<span letter_spacing="6000">HERMES</span>', font_size=18)
+# Note: Pango letter_spacing is in 1/1024 of a point
+```
+
+## Animation Errors
+
+**Invisible animation** -- mobject never added:
+```python
+# WRONG: circle = Circle(); self.play(circle.animate.set_color(RED))
+# RIGHT: self.play(Create(circle)); self.play(circle.animate.set_color(RED))
+```
+
+**Transform confusion** -- after Transform(A, B), A is on screen, B is not. Use ReplacementTransform if you want B.
+
+**Duplicate animation** -- same mobject twice in one play():
+```python
+# WRONG: self.play(c.animate.shift(RIGHT), c.animate.set_color(RED))
+# RIGHT: self.play(c.animate.shift(RIGHT).set_color(RED))
+```
+
+**Updater fights animation**:
+```python
+mob.suspend_updating()
+self.play(mob.animate.shift(RIGHT))
+mob.resume_updating()
+```
+
+## Rendering Issues
+
+**Blurry output**: Using -ql (480p). Switch to -qm/-qh for final.
+
+**Slow render**: Use -ql during development. Reduce Surface resolution. Shorter self.wait().
+
+**Stale output**: `manim -ql --disable_caching script.py Scene`
+
+**ffmpeg concat fails**: All clips must match resolution/FPS/codec.
+
+## Common Mistakes
+
+**Text clips at edge**: `buff >= 0.5` for `.to_edge()`
+
+**Overlapping text**: Use `ReplacementTransform(old, new)`, not `Write(new)` on top.
+
+**Too crowded**: Max 5-6 elements visible. Split into scenes or use opacity layering.
+
+**No breathing room**: `self.wait(1.5)` minimum after reveals, `self.wait(2.0)` for key moments.
+
+**Missing background color**: Set `self.camera.background_color = BG` in every scene.
+
+## Debugging Strategy
+
+1. Render a still: `manim -ql -s script.py Scene` -- instant layout check
+2. Isolate the broken scene -- render only that one
+3. Replace `self.play()` with `self.add()` to see final state instantly
+4. Print positions: `print(mob.get_center())`
+5. Clear cache: delete `media/` directory