modular_aphelion/modules/custom_sprites/code/regions.dm 
| /proc/custom_sprite_present_regions | The marking regions this body can be painted on right now, in draw order. |
|---|---|
| /proc/custom_sprite_region_color | Region N's ID color. Regions paint nothing else, so a pixel of this color is unambiguous. |
| /proc/custom_sprite_region_id_drawing | A solid drawing of region N's ID color across one editing mask, or null when the mask is empty. |
| /proc/custom_sprite_region_map | Which region owns each canvas pixel, in every view. |
| /proc/cmp_custom_sprite_region_layer | Orders custom_sprite_region_map()'s images by layer, lowest first. sort_list() is stable, so region order holds within a layer. |
| /proc/custom_sprite_region_fallback | The region that dominates one blended pixel, as its region character. |
| /proc/custom_sprite_region_owner | The region owning a canvas pixel (0-based), or null. |
| /proc/custom_sprite_region_mask | The paintable mask of a region map: every pixel an unlocked region owns. locked holds region characters. |
| /proc/custom_sprite_merge_cover_rows | One view's cover rows with each pixel judged against the layer its own region's paint draws on. |