Issue was caused by MFACE layer adding for even DM without tessellated faces
which lead to adding new layer but with NULL data. This causes issues when layer
with faces (after extrude) was attempting to add because currently CD only checks
if layer type exists but does not check for size of the layer.
Solved by not adding MFACE layer if there's no tessellated faces.
This idea is borrowed from the multires modifier, which already
checked if the object was in sculpt mode and, if so, created the
PBVH. That check is now moved higher up the chain into
mesh_build_data(), so that it occurs for CDDerivedMesh too.
This also replaces an assert in cdDM_getPBVH for tesselated mesh faces
with a call to create them if missing.
- spelling - turns out we had tessellation spelt wrong all over.
- use \directive for doxy (not @directive)
- remove BLI_sparsemap.h - was from bmesh merge IIRC but entire file commented and not used.
These changes are to make the bmesh api more consistent and easier to learn, grouping similar functions which is convenient for autocomplete.
This uses similar convention to RNA.
* use face/loop/edge/vert as a prefix for functions.
* use 'elem' as a prefix too for functions that can take any type with a BMHeader.
* changed from camel case to underscore separated (like RNA).
In fact, we have to add a CD_WEIGHT_MCOL layer (if not yet present) when updating CD_WEIGHT_MLOOPCOL, else with modifiers modifying the topology (like subsurf), it will sigsev.
That step should probably be done at tesselation time, though…
Also simplifies DM_update_weight_mcol: no need to update CD_WEIGHT_MCOL here, as it is anyway recreated from CD_WEIGHT_MLOOPCOL at tesselation time. Only commented out code for now.
User side:
* Preview for DynamicPaint should keep the same behavior (for now). Weight preview should be somawhat quicker, though.
* Preview for WeightVG modifiers is only active in WeightPaint mode, and if the affected vgroup is the active one.
* Last active preview modifier in stack wins!
Note: that modifier preview topic is yet to be further refined, quite raw/incomplete for now.
Dev side:
* In draw code, renamed DRAW_DYNAMIC_PAINT_PREVIEW flag to DRAW_MODIFIERS_PREVIEW
* Removed use of MOD_DPAINT_PREVIEW_READY in DynamicPaint code (seems unecessary, and if it was, should be of more general scope).
* Added eModifierTypeFlag_UsesPreview to ModifierTypeFlag, for modifiers that can generate some preview data.
* Added three new modifier funcs, to handle preview modifiers in draw code / mod stack.
* For weights preview: added the generic DM_update_weight_mcol func, which can update WEIGHT_MCOL layer with either a given array of weights (currently used by DynamicPaint only), or from current active vgroup(s).
So now, draw code is fully generic (i.e. no more modifier-type checking in it). Mod stack code is generic to some extent, but will need more work.
- made editbmesh_calc_modifiers() ensure tessfaces, this has the advantage that if the tessfaces are already created they wont get re-made as was happening before.
through Object.dm_info('SOURCE/DEFORM/FINAL')
this is to help tracking down issues with modifiers where loosing data
layers between modifiers can cause bugs, also to helo with comparing
bmesh/trunk's modifier stack.
- in the case of deform modifiers this is very safe (assuming the mods themselves dont need tessface data), since the DM is freed right after, so this is an easy speedup.
- in the case of bevel and split edge modifiers this should still work out fine since mods that need tessface data will generate it.
