Draw in color 15 only. No UI.

bitplane-thingie.p8

@@ -0,0 +1,121 @@
+pico-8 cartridge // http://www.pico-8.com
+version 41
+__lua__
+-- bitplane-thingie
+-- by kistaro
+-- mastodon: @kistaro@dragon.style
+-- matrix: @kistaro:chromaticdragon.net
+--
+-- dev tool for experimenting
+-- with bitplanes and palettes
+
+function _init()
+ cls()
+ -- reset bitplanes
+ poke(0x5f5e, 0xff)
+ -- enable mouse
+ poke(0x5f2d, 0x1)
+ 
+ -- reset mouse position
+ last_segment = nil
+ segment = nil
+ was_click = false
+ cx, cy = 0, 0
+ 
+ -- reset color
+ plane_mask = 0xff
+end
+
+function _update60()
+ restore_under_cursor()
+ if stat(34) & 0x1 == 0 then
+  -- mouse up
+  was_click = false
+  segment = nil
+  return
+ end
+
+ -- mouse down
+ local mouse_x = stat(32)
+ local mouse_y = stat(33)
+ 
+ if mouse_y >= 112 then
+  if segment then
+   mouse_y = 111
+  elseif not was_click then
+   handle_ui_click(x, y)
+  end
+ end
+ 
+ if mouse_y < 112 then
+  local r = 1
+  if segment then
+   local dx = mouse_x - segment[1]
+   local dy = mouse_y - segment[2]
+   r = sqrt(dx*dx+dy*dy)
+  end
+  segment = {mouse_x, mouse_y, r}
+ end 
+ 
+ was_click = true
+end
+
+function _draw()
+ draw_ui()
+ draw_segment()
+ draw_cursor()
+end
+
+-->8
+-- draw_segment
+
+function draw_segment()
+ if (not segment) return
+ 
+ color(0xff)
+ poke(0x5f5e, plane_mask)
+ circfill(unpack(segment))
+end
+
+-->8
+-- ui (and click)
+
+function draw_ui()
+ poke(0x5f5e, 0xff)
+end
+
+function handle_ui_click(x, y)
+end
+-->8
+-- draw_cursor
+
+function draw_cursor()
+ cx, cy = stat(32), stat(33)
+ 
+ -- save blob under cursor to
+ -- corner of sprite sheet
+ -- to restore on next frame
+ poke(0x5f54, 0x60)
+ poke(0x5f55, 0x00)
+ palt(0, false)
+ sspr(cx, cy, 8, 8, 120, 24)
+ palt(0, true)
+ poke(0x5f54, 0x00)
+ poke(0x5f55, 0x60)
+ spr(stat(34)+1, cx, cy)
+end
+
+function restore_under_cursor()
+ palt(0, false)
+ sspr(120, 24, 8, 8, cx, cy)
+ palt(0, true)
+end
+__gfx__
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