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Re: displaying concave polygons with openGL
by Bert Freudenberg
::
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It means that you can employ any method you fancy for rendering the
polygons, without being overly concerned with efficiency, since the
rendered map would be reused for many frames. Squeak's Balloon engine
can render general polygons with holes using 4x4 antialiasing quite
efficiently, which would hopefully be more than good enough for your
needs:
drawGeneralPolygon:color:borderWidth:borderColor:
- Bert -
On 21.04.2008, at 16:46, Baveco, Hans wrote:
> Ah, sorry, it is an unknown chapter to me, this texture mapping. Are
> there examples available in Croquet how to do this? How would it
> help me
> solve the concave polygon problem? (googling it gives mostly
> references
> to GLU)
>
> Hans
>
>> -----Original Message-----
>> From: popp@... [mailto:popp@...] On
>> Behalf Of Bert Freudenberg
>> Sent: maandag 21 april 2008 16:17
>> To: croquet-dev@...
>> Subject: Re: [croquet-dev] displaying concave polygons with openGL
>>
>> What I meant was rendering the data into textures as
>> required, not loading them from bitmap files.
>>
>> - Bert -
>>
>> On 21.04.2008, at 15:46, Baveco, Hans wrote:
>>
>>>
>>> Yes, that is the easy way. However, I would like to add GIS
>>> functionality: creating the polygons from a spatial database and
>>> directly display them in Croquet, without the need of a GIS
>> inbetween
>>> that would export the map as an image...
>>> Spatial data would be e.g. in ESRI's shapefile (.shp) or
>> export (.e00)
>>> format.
>>>
>>> Hans
>>>
>>>
>>>
>>>
>>> On 21.04.2008, at 15:08, Baveco, Hans wrote:
>>>
>>>> HI,
>>>> I am looking for a way to display polygons in Croquet. I
>> need this to
>>>> be able to show maps in Croquet. With openGL only simple (convex,
>>>> without holes, etc) polygons can be rendered. Non-simple polygons
>>>> need
>>>
>>>> to be tesselated (converted into a set of convex polygons). GLUT
>>>> apparently can be used to build this tesselation, but I
>> find it very
>>>> hard to understand how exactly to do this... Is it really the only
>>>> way
>>>
>>>> to achieve my goal (appart from doing this tesselation in Squeak,
>>>> which might be pretty slow for large maps, say consisting of upto
>>>> 100.000 polygons)? Or is there a workaround? (I suppose others may
>>>> have felt the need to display such polygons....). Cairo
>> also seems to
>>>> be able to do this tesselation, but can it be used in
>> Croquet? (a 2D
>>>> rendering would be ok),
>>>
>>>
>>> Unless your maps are dynamic, displaying them as a texture would be
>>> most appropriate IMHO. It's hard to be more specific
>> without knowing
>>> the details and requirements.
>>>
>>> - Bert -
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
polygons, without being overly concerned with efficiency, since the
rendered map would be reused for many frames. Squeak's Balloon engine
can render general polygons with holes using 4x4 antialiasing quite
efficiently, which would hopefully be more than good enough for your
needs:
drawGeneralPolygon:color:borderWidth:borderColor:
- Bert -
On 21.04.2008, at 16:46, Baveco, Hans wrote:
> Ah, sorry, it is an unknown chapter to me, this texture mapping. Are
> there examples available in Croquet how to do this? How would it
> help me
> solve the concave polygon problem? (googling it gives mostly
> references
> to GLU)
>
> Hans
>
>> -----Original Message-----
>> From: popp@... [mailto:popp@...] On
>> Behalf Of Bert Freudenberg
>> Sent: maandag 21 april 2008 16:17
>> To: croquet-dev@...
>> Subject: Re: [croquet-dev] displaying concave polygons with openGL
>>
>> What I meant was rendering the data into textures as
>> required, not loading them from bitmap files.
>>
>> - Bert -
>>
>> On 21.04.2008, at 15:46, Baveco, Hans wrote:
>>
>>>
>>> Yes, that is the easy way. However, I would like to add GIS
>>> functionality: creating the polygons from a spatial database and
>>> directly display them in Croquet, without the need of a GIS
>> inbetween
>>> that would export the map as an image...
>>> Spatial data would be e.g. in ESRI's shapefile (.shp) or
>> export (.e00)
>>> format.
>>>
>>> Hans
>>>
>>>
>>>
>>>
>>> On 21.04.2008, at 15:08, Baveco, Hans wrote:
>>>
>>>> HI,
>>>> I am looking for a way to display polygons in Croquet. I
>> need this to
>>>> be able to show maps in Croquet. With openGL only simple (convex,
>>>> without holes, etc) polygons can be rendered. Non-simple polygons
>>>> need
>>>
>>>> to be tesselated (converted into a set of convex polygons). GLUT
>>>> apparently can be used to build this tesselation, but I
>> find it very
>>>> hard to understand how exactly to do this... Is it really the only
>>>> way
>>>
>>>> to achieve my goal (appart from doing this tesselation in Squeak,
>>>> which might be pretty slow for large maps, say consisting of upto
>>>> 100.000 polygons)? Or is there a workaround? (I suppose others may
>>>> have felt the need to display such polygons....). Cairo
>> also seems to
>>>> be able to do this tesselation, but can it be used in
>> Croquet? (a 2D
>>>> rendering would be ok),
>>>
>>>
>>> Unless your maps are dynamic, displaying them as a texture would be
>>> most appropriate IMHO. It's hard to be more specific
>> without knowing
>>> the details and requirements.
>>>
>>> - Bert -
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
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