Latimerius,
I think you are correct. There is another section of the xml file:
<triangles count="12" material="Material2">
<input offset="0" semantic="VERTEX" source="#ID7" />
<p>0 1 2 1 0 3 4 5 6 5 4 7 8 9 10 9 8 11 12 13 14
13 12 15 16 17 18 17 16 19 20 21 22 21 20 23</p>
</triangles>
I did not notice until your note. I looked at it further. The
numbers are not consecutive. It starts off as
0 1 2 and ends in 23 but it appears that it is saying triangle
4(counting from 1) is specified by three vertices encoded at offset
1.
I'll see if I can use this. Be right back.
John
On Thu, Oct 27, 2011 at 12:50 PM, Latimerius <l4t1m3r...@googlemail.com> wrote:
> Looks like it uses GL_TRIANGLES in indexed mode (probably the most
> common way by far).
>
> That way, each side of your box has 4 vertices. The two triangles
> used to render the side use 6 indices to refer to the 4 vertices. So
> you should have 6*4=24 vertices and 6*6=36 indices.
>
> That matches your .dae if I'm not mistaken - the <p> XML element
> contains your 36 indices, the <float_array> element has 72 floats
> which is the 24 vertices, 3 float coordinates each (24*3=72).
>
> On Thu, Oct 27, 2011 at 5:15 PM, John Davis <davi...@gmail.com> wrote:
>> FWIW,
>>
>> I am simply taking the data from the xml file and copying it and then
>> pasting into an array.
>> I am not doing a automatic read or anything. One thing which puzzles
>> me is the number of vertices
>> in the file.
>>
>> For instance, a rectangle has six sides. If you use two triangles to
>> draw each side
>> that is 6 sides * 2 triangles per side for a total of 12 triangles.
>> This agrees with .xml file
>> which says says there are 12 triangles.
>>
>> From the xml file:
>> <triangles count="12" material="Material2">
>> <input offset="0" semantic="VERTEX" source="#ID7" />
>> <p>0 1 2 1 0 3 4 5 6 5 4 7 8 9 10 9 8 11 12 13 14
>> 13 12 15 16 17 18 17 16 19 20 21 22 21 20 23</p>
>>
>>
>> If you use 3 coordinates for each vertice of a triangle and a triangle
>> has three vertices,
>> then you have 3 * 3 *12 = 9*12 = 108 values of x, y, and z.
>>
>> However the xml file has 72. From the xml file:
>> <float_array id="ID8" count="72">22.62976164142344
>> 29.52755905511811 0 0 0 0 0 29.52755905511811 0 22.62976164142344 0 0
>> 22.62976164142344 0 13.77952755905512 0 0 0 22.62976164142344 0 0 0 0
>> 13.77952755905512 0 29.52755905511811 13.77952755905512 0 0 0 0 0
>> 13.77952755905512 0 29.52755905511811 0 0 29.52755905511811
>> 13.77952755905512 22.62976164142344 29.52755905511811 0 0
>> 29.52755905511811 0 22.62976164142344 29.52755905511811
>> 13.77952755905512 22.62976164142344 29.52755905511811 0
>> 22.62976164142344 0 13.77952755905512 22.62976164142344 0 0
>> 22.62976164142344 29.52755905511811 13.77952755905512
>> 22.62976164142344 0 13.77952755905512 0 29.52755905511811
>> 13.77952755905512 0 0 13.77952755905512 22.62976164142344
>> 29.52755905511811 13.77952755905512</float_array>
>>
>> So I am thinking it does not draw individual triangles using
>> GL_TRIANGLES mode. Instead it uses
>> GL_TRIANGLE_STRIP or GL_TRIANGLE_FAN mode where it is sharing vertices.
>> I'm not sure though.
>>
>> Maybe my math is wrong, but if you share triangles the number of verts
>> required is verts' as this table shows.
>>
>> Triangles Verts Verts'
>> 1 3 3
>> 2 6 4
>> 3 9 5
>> 4 12 6
>> 5 15 7
>> 6 18 8
>> .... verts' = tri+2
>> 12 36 14
>>
>> and 36*3 = 108 values
>> but 14*3 = 42 values not 72
>>
>> John
>>
>> On Thu, Oct 27, 2011 at 10:22 AM, J Handal <jhand...@gmail.com> wrote:
>>>
>>> I think is error is due to an incompatible file extension .dae file,
>>> AFIK android use .obj files with android(and other extensions??) but
>>> not Collada files.
>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "Android Developers" group.
>>> To post to this group, send email to android-developers@googlegroups.com
>>> To unsubscribe from this group, send email to
>>> android-developers+unsubscr...@googlegroups.com
>>> For more options, visit this group at
>>> http://groups.google.com/group/android-developers?hl=en
>>
>>
>>
>> --
>> John F. Davis
>>
>> 独树一帜
>>
>> --
>> You received this message because you are subscribed to the Google
>> Groups "Android Developers" group.
>> To post to this group, send email to android-developers@googlegroups.com
>> To unsubscribe from this group, send email to
>> android-developers+unsubscr...@googlegroups.com
>> For more options, visit this group at
>> http://groups.google.com/group/android-developers?hl=en
>
> --
> You received this message because you are subscribed to the Google
> Groups "Android Developers" group.
> To post to this group, send email to android-developers@googlegroups.com
> To unsubscribe from this group, send email to
> android-developers+unsubscr...@googlegroups.com
> For more options, visit this group at
> http://groups.google.com/group/android-developers?hl=en
--
John F. Davis
独树一帜
--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
