Indices list in shapes

Troubleshooting General Help
1

Can i create shapes without an indices list?

Can the LWJGLRenderer draw this?

2
"aschwalb" wrote:
Can i create shapes without an indices list?
Can the LWJGLRenderer draw this?
Yes you can. Look at the trimesh class.
3

Indices are required for all Trimeshes and all shapes extend trimeshes. So, no, you cannot create shapes without index lists.

4

How would OpenGL know what to draw without indices?

5
"renanse" wrote:
How would OpenGL know what to draw without indices?

Geometry has no indices, it draws the triangles in order(I think).
6

You can’t draw Geometry directly.

7
"renanse" wrote:
You can't draw Geometry directly.
:// That is what hapens in directx then.
8

I’m not sure, but i think that is also possible.

In xith3d i can choose e.g a TriangleGeometryArray or

an IndexedTriangleGeometryArray.

I think the vertices in its buffer must only lie in the right order

how the triangles must be drawn.

In the lwjgl library documentation i have searched for a right method

to do this job, but all methods and parameters are undocumented, so i have no chance to find a right.

Why they have created a javadoc at all?

9

Sorry, should’ve been more clear. The way we render in jME, you currently need indices. And by Geometry, I meant our Geometry class.

10

At last, i have found it!!



I have tested it and at runs without indices.

I only set a dummy indices array new int[1] and change in LWJGLRenderer in method draw(TriMesh t) the following call

’ GL12.glDrawRangeElements(GL11.GL_TRIANGLES, 0, t.getVertQuantity(), indices); ’ to

‘GL11.glDrawArrays(GL11.GL_TRIANGLES, 0, t.getVertQuantity());’

That does the job.

11

We have chosen certain methods for a reason, generally related to speed. Why not just generate a simple indices list? It’s extremely easy to do.

12

Objects without indices are faster created, i think.

Also, extensive objects can have an indices list that is not

so simple how a cube list is. Take 10 objects, each of them has 5000 indices, that takes a lot of extra memory.

Using only wireframe- or colored objects, the code can be much simpler

as for textured objects. This objects needs extra attention between

vertices and indices or the object shows a bit odd.



<<Related to speed>>

Going straight forward through an array is faster, i think, as first

load an offset from another array an than takes the value from

the other array.