akkartik/snap.love - Change TZNPEHB3BRUHATVYAODURZUR45TYV62HYWQK5SUXHAOLVGYJVP7AC

snapshot: insight

Ugh, it's been in front of my eyes all along. The logs have been repeatedly showing a recurrence within a single frame:

key press -> update Viewport.y from screen_top -> A -> B -> update_editor_box -> update screen_top from Viewport.y

We need both those updates, but both should never occur at the same time to the same node.

I think this is why screen panning works if I take out the scale inside update_editor_box: the scale has already happened "once" in updating Viewport.y, and it doesn't converge if we perform it a second time in a frame. But the solution is just to do one or the other to a node, never both.

I knew this (learned it the hard way) when I first built pensieve.love, and I had an assertion to avoid it. But my assertion was brittle, and it kept failing, and I took it out, and then I slowly took out all the code that prevented this recurrence.

Created by Kartik K. Agaram on October 25, 2023

TZNPEHB3BRUHATVYAODURZUR45TYV62HYWQK5SUXHAOLVGYJVP7AC

Dependencies

In channels

main

Change contents

Replacement in 0034-dump_state at line 4 [2.28]

B:BD[2.97] → [2.97:271]

	print('viewport', Viewport.y)
	print('node', Page.data[1].y)
	print('node renders from', Page.data[1].editor.top)
	print('screen top', Page.data[1].editor.screen_top1.line)

[2.97]

[2.271]

	print('viewport', Viewport.y, 'spx')
	local node = Page.data[1]
	print('node', node.y, 'spx')
	print('line height', node.editor.line_height, 'vpx')
	print('node renders from', node.editor.top, 'vpx')
	print('screen top', node.editor.screen_top1.line)
	print('invariant', Viewport.y-node.y+node.editor.top - y_of_schema1(node.editor, node.editor.screen_top1))

Replacement in 0034-dump_state at line 12 [2.28]

B:BD[2.285] → [2.285:360]

	print('y of line', l, y_of_schema1(Page.data[1].editor, {line=l, pos=1}))

[2.285]

[2.360]

	print('y of line', l, y_of_schema1(node.editor, {line=l, pos=1}), 'spx')

Insertion in 0030-update_editor_box at line 3 [3.26]
[3.137]
[4.31]
```
	edit.update_font_settings(node.editor, scale(20))
```
Deletion in 0030-update_editor_box at line 16 [3.26]
∅:D[5.400] → [3.542:593]
B:BD[3.542] → [3.542:593]
```
	edit.update_font_settings(node.editor, scale(20))
```

Replacement in 0028-A at line 3 [7.6019]

B:BD[6.1534] → [6.1534:1834]

	-- translate Page to Surface
	while #Surface > 3 do table.remove(Surface) end  -- HACK
	local red = false
	for x=-1000,2000,300 do
		for y=-10000,10000,200 do
			add_thick_line({type='line', data={x,y, x+200,y+200, x,y+400}, r=red and 1 or 0,g=red and 0 or 0.5,b=0}, 10)
			red = not red
		end
	end

[6.1534]

[6.1834]

	Surface = {}

Deletion in 0028-A at line 5 [7.6019]
B:BD[6.1880] → [6.1880:1929]
```
	compute_layout(Page2, Page2.x,Page2.y, Surface)
```
Replacement in 0028-A at line 8 [7.6019]
∅:D[8.356] → [5.519:523]
∅:D[6.2020] → [5.519:523]
B:BD[7.6661] → [5.519:523]
```
end
```
[6.2020]
```
end
```

Insertion in 0026-on.draw at line 3 [10.238692]

[9.66]

	love.graphics.line(50, 0, 50, App.screen.height)
	for i=0,100 do
		love.graphics.print(tostring(i), 30, i*100)
	end
	local vy0 = vy(0)
	love.graphics.line(100, vy0, 100, App.screen.height)
	for i=0,100 do
		love.graphics.print(tostring(i), 80, vy0+i*100)
	end

Replacement in 0026-on.draw at line 15 [10.238692]

B:BD[9.190] → [11.498:551]

		love.graphics.print(tostring(i), vx(0), vy(i*100))

[9.190]

[9.244]

		love.graphics.print(tostring(i), vx(0)-20, vy(i*100))

Replacement in 0026-on.draw at line 39 [10.238692]
B:BD[10.241398] → [12.380:384]
```
end
```
[10.241398]
```
end
```
Replacement in 0020-Page at line 73 [13.55929]
B:BD[13.56777] → [13.56777:56813]
```
        width=400, bg={r=1,g=1,b=0}
```
[13.56777]
[13.56813]
```
        width=400, bg={r=0,g=0.8,b=0}
```
Replacement in 0020-Page at line 76 [13.55929]
B:BD[13.57533] → [11.910:912]
```
}
```
[13.57533]
```
}
```

snapshot: insight

Dependencies

In channels

Change contents

Replacement in 0034-dump_state at line 4 [2.28]

Replacement in 0034-dump_state at line 12 [2.28]

Insertion in 0030-update_editor_box at line 3 [3.26]

Deletion in 0030-update_editor_box at line 16 [3.26]

Replacement in 0028-A at line 3 [7.6019]

Deletion in 0028-A at line 5 [7.6019]

Replacement in 0028-A at line 8 [7.6019]

Insertion in 0026-on.draw at line 3 [10.238692]

Replacement in 0026-on.draw at line 15 [10.238692]

Replacement in 0026-on.draw at line 39 [10.238692]

Replacement in 0020-Page at line 73 [13.55929]

Replacement in 0020-Page at line 76 [13.55929]