[Bf-committers] In need for help/documentation for modifiers

[Tobias Oelgarte]

So far i edited 10 different places. But if i try to compile it, i get 
this confusing error message from makesdna:

...
scons: 
`/media/Trekstor_01/temp/blender-trunk/build/linux2/lib/libbf_imbuf.a' 
is up to date.
"/media/Trekstor_01/temp/blender-trunk/build/linux2/makesdna" 
/media/Trekstor_01/temp/blender-trunk/build/linux2/source/blender/makesdna/intern/dna.c
Running makesdna at debug level 0
    Program version: $Id: makesdna.c 31990 2010-09-18 03:46:13Z 
campbellbarton $
Sizeerror 8 in struct: RestoreVolumeModifierData (add 4 bytes)
scons: *** 
[/media/Trekstor_01/temp/blender-trunk/build/linux2/source/blender/makesdna/intern/dna.c] 
Error 1
scons: building terminated because of errors.

So far as i read the code, it checks if the struct has the correct size. 
But is something wrong with my struct? I can't see it:

from DNA_modifier_types.h:
  typedef struct RestoreVolumeModifierData {
      ModifierData modifier;
      // own data
      float volume;            /* volume that mesh should have after 
applying modifier */
      char name[32];           /* name of vertexgroup that defines wich 
areas can grow/shrink */
  } RestoreVolumeModifierData;



Phil Gosch schrieb:
>   Hi, I found this link pretty helpful:
>
> http://enja.org/2010/05/24/blender-creating-a-custom-modifier/
>
> Best wishes, phil (SaphireS)
>
> Am 08.10.2010 12:44, schrieb Tobias Oelgarte:
>   
>> At least this is some starting point. A simple documentation on this
>> could be really handy. I will try to setup a basic modifier and see if i
>> run in any trouble. If so, i will ask back, since this could also be
>> helpfull, if you decide to write a documentation on this. For now i will
>> spend my time to read more into the code.
>>
>> Thank you. Without this i might have searched for hours/days and
>> probably given up frustrated.
>>
>> Jeroen Bakker schrieb:
>>     
>>> Hi,
>>>
>>> I have a small step by step mind dump, but have not yet had time to
>>> write the complete documentation about it. see below. there is also a
>>> developer website who mentions it, but cannot find it right now.
>>>
>>> Add custom modifier
>>> 1. DNA_modifier_types.h -->  add ModifierType enumeration (must start
>>> with eModifierType_[NAME])
>>> 2. DNA_modifier_types.h -->  Add [NAME]ModifierData struct. first field
>>> must be ModifierData modifier
>>> 3. rna_modifier.c -->      {eModifierType_[NAME], "[NAME]",
>>> ICON_MOD_PHYSICS, "Surface", ""},
>>>
>>> static void rna_def_modifier_test(BlenderRNA *brna)
>>> {
>>>       StructRNA *srna;
>>>
>>>       srna= RNA_def_struct(brna, "TestModifier", "Modifier");
>>>       RNA_def_struct_ui_text(srna, "Test Modifier", "just a test");
>>>       RNA_def_struct_sdna(srna, "TestModifierData");
>>>       RNA_def_struct_ui_icon(srna, ICON_MOD_PARTICLES);
>>> }
>>> add sdna fields
>>> static StructRNA* rna_Modifier_refine(struct PointerRNA *ptr)
>>>    add case
>>>
>>> call method from register
>>>
>>> 4 modifier.c
>>>           mti = INIT_TYPE(Test);
>>>           mti->type = eModifierTypeType_Constructive;
>>>           mti->flags = eModifierTypeFlag_AcceptsMesh;
>>>           mti->initData = testModifier_initData; // method to be called
>>> when created
>>>           mti->copyData = testModifier_copyData; // method to be called
>>> when copied
>>>           mti->applyModifier = testModifier_applyModifier; // method to
>>> be called when applied
>>>           mti->applyModifierEM = testModifier_applyModifierEM; // method
>>> to be called when applied
>>> /** test modifier **/
>>> static void testModifier_initData(ModifierData *md)
>>> {
>>> }
>>>
>>> static void testModifier_copyData(ModifierData *md, ModifierData *target)
>>> {
>>> }
>>> static DerivedMesh *testModifier_applyModifier(ModifierData *md,
>>>                              Object *ob,
>>>                              DerivedMesh *dm,
>>>                              int useRenderParams,
>>>                              int isFinalCalc)
>>> {
>>>       return dm;
>>> }
>>> static DerivedMesh *testModifier_applyModifierEM(ModifierData *md,
>>>                                Object *ob,
>>>                                EditMesh *editData,
>>>                                DerivedMesh *derivedData)
>>> {
>>>       return testModifier_applyModifier(md, ob, derivedData, 0, 1);
>>> }
>>>
>>> 5. add user interface panel.
>>> properties_data_modifier.py
>>> class DATA_PT_modifiers add method [NAME]
>>>
>>> 6. implement modifier.
>>>
>>>
>>>
>>>
>>> On 10/08/2010 12:30 PM, Tobias Oelgarte wrote:
>>>
>>>       
>>>> Hello,
>>>>
>>>> Im currently looking into the sources of blender and try to understand
>>>> how the modifiers are working. Writing a modifier seams to be simple,
>>>> but on the other side there are many other files that are keeping lists
>>>> of them (to know which are available). This is somehow like finding all
>>>> needles in a haystack.
>>>>
>>>> Is there a documentation on modifiers, that lists all the files that
>>>> need to be changed if you write/add your own modifier? Need this files
>>>> to be changed, or will they be updated automatically? (guess not)
>>>>
>>>> Somehow i miss some document that points out how i can write my own
>>>> modifier from scratch (including gui etc.). At least a very simple
>>>> example would be nice.
>>>>
>>>> Currently i developed code to write a so called RestoreVolume-Modifer,
>>>> that ensures that a closed mesh keeps/restores it's original volume
>>>> after deformations (due to other modifiers). Simplest example would be a
>>>> muscle that contracts and will grow on the sides (controllable by vertex
>>>> group), because of the loss of volume in length.
>>>>
>>>> Any suggestions or hints?
>>>>
>>>> Best wishes Tobias Oelgarte
>>>> _______________________________________________
>>>> Bf-committers mailing list
>>>> Bf-committers at blender.org
>>>> http://lists.blender.org/mailman/listinfo/bf-committers
>>>>
>>>>
>>>>
>>>>         
>>>       
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>
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