# Rendering 3D Box **URL:** \ **Category:** PowerVR Insider\ **Tags:** pvrshaman\ **Created:** [June 21, 2013, 8:18am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814 "2013-06-21T08:18:13Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 8:18am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/1 "2013-06-21T08:18:13Z")
Hi, I have successfully rendered a triangle on the PandaBoard. But when I try rendering a 3D box (Indexed buffer object comes into picture), I can compile it but during running , a window shows but the box is not rendered. It suddenly turns black and prints the following line on the terminal continuously : PVR:(Error): Index offset 608592 is larger than index buffer size 192 [1340, /drawvarray.c] Can anyone tell me where did I go wrong ? ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 10:03am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/2 "2013-06-21T10:03:13Z")
Hello how did you do your box ? was it base on a list of triangle indexed or not ? example : ````auto GLushort indices[] =
{
4, 5, 6, 4, 6, 7,
1, 0, 3, 1, 3, 2,
0, 4, 7, 0, 7, 3,
5, 1, 2, 5, 2, 6,
0, 4, 5, 0, 5, 1,
3, 7, 6, 3, 6, 2
};

glGenBuffers(1, &m_BoxIBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_BoxIBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); ```

david
```` ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 10:10am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/3 "2013-06-21T10:10:22Z")
The great great PVRShaman can help for fast testing , it allow as well to create Open Built in Object menu and add a custom effect and a simple shader , it work very well and it s fast. ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 10:18am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/4 "2013-06-21T10:18:57Z")
I did exactly the same. The list of triangles was indexed and consisted of 36 indices. The only difference is that I used GLuint indices[]. Please also tell the parameters of glDrawElements(). Mine is : glDrawElements(GL\_TRIANGLES, numfaces \* 3, GL\_UNSIGNED\_INT, indices); ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 10:31am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/5 "2013-06-21T10:31:45Z")
```auto glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_BoxIBO);
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_SHORT, NULL); ``` ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 10:33am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/6 "2013-06-21T10:33:50Z")
Why should the last parameter be NULL ? ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 10:41am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/7 "2013-06-21T10:41:44Z")
Well, making the last parameter NULL removed the error but the box doesn’t get rendered. There is only the background. ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 10:43am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/8 "2013-06-21T10:43:49Z")
it s an indexed triangle list !!! ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 10:47am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/9 "2013-06-21T10:47:39Z")
elsewhere i will use glDrawArrays the SDK have a lot of good material on all the spec , i like to look at it , there is so much to learn !!! ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 10:47am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/10 "2013-06-21T10:47:45Z")
void glDrawElements( GLenum mode, GLsizei count, GLenum type, const GLvoid \* indices); indices - Specifies a pointer to the location where the indices are stored. Why should we pass NULL to the pointer to the location i.e. indices. ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 11:14am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/11 "2013-06-21T11:14:21Z")
It s not mandatory , it depend of your choice of data structure index /not index list , strip not strip etcetc as we are in an index list you can select from witch indices you want to start ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 11:18am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/12 "2013-06-21T11:18:51Z")
How do we define an indexed list data structure. I just parsed the coordIndex node of the VRML file i.e. : coordIndex [ 0, 1, 2, -1, 2, 3, 0, -1, 3, 2, 4, -1, 4, 5, 3, -1, 5, 4, 7, -1, 7, 6, 5, -1, 6, 7, 1, -1, 1, 0, 6, -1, 6, 0, 3, -1, 3, 5, 6, -1, 1, 7, 2, -1, 7, 4, 2, -1, ] removed the -1s and copied the array into a GLuint indices[36]. Any idea why the box is invisible on changing the parameter to NULL ? ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 11:27am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/13 "2013-06-21T11:27:38Z")
i didnt check your values i assume there are right 🙂 i am too lazy today… `GLushort coordIndex[] = { 0, 1, 2, 2, 3, 0, 3, 2, 4, 4, 5, 3, 5, 4, 7, 7, 6, 5, 6, 7, 1, 1, 0, 6, 6, 0, 3, 3, 5, 6, 1, 7, 2, 7, 4, 2 }; glGenBuffers(1, &BoxIBO); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BoxIBO); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(coordIndex), coordIndex, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); Rendering is : glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BoxIBO); glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_SHORT, NULL);` regards david guimard ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 12:08pm UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/14 "2013-06-21T12:08:20Z")
Hey, got the box rendered. 🙂 I don’t know for some reason sizeof(indices) was returning 4, so I tried with (numfaces\*(3\*sizeof(GL\_UNSIGNED\_SHORT)) and parameter as NULL and it worked ! Thanks for your replies. ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 12:10pm UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/15 "2013-06-21T12:10:20Z")
GOOD STUFF what s your next move then ? ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 21, 2013, 12:18pm UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/16 "2013-06-21T12:18:43Z")
Now I’ll proceed to provide navigation features in the scene. ---
**Author:** ![dgu](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@dgu](https://forums.imgtec.com/u/dgu)\ **Post date:** [June 21, 2013, 12:21pm UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/17 "2013-06-21T12:21:52Z")
ok good luck ---
**Author:** ![hellboy](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@hellboy](https://forums.imgtec.com/u/hellboy)\ **Post date:** [June 24, 2013, 9:11am UTC](https://forums.imgtec.com/t/rendering-3d-box/1814/18 "2013-06-24T09:11:00Z")
Hey, I think I got it wrong. When I rotated the camera to look the box from a different angle, I saw that it’s actually rendered two dimensionally. Do you know what the problem may be ?