difference between INDEXED GEOMETRY and NON-INDEXED GEOMETRY

Engines, Libraries and Tools Xith3D Forums
#1

hi people…can nyone plzz explain me that what are the differences between indexed geometry n non-indexed geometry…actually i was reading about Triangle Array and Indexed Triangle Array…and i was surprised to see that the description was exactly similar …

public class IndexedTriangleArray

extends IndexedGeometryArray

The IndexedTriangleArray object draws the array of vertices as individual
triangles. Each group of three vertices defines a triangle to be drawn.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You’re sure about that? Where would be the difference to TriangleArray?

And here the JAVADOC for TriangleArray:

public class TriangleArray
extends GeometryArray

The TriangleArray object draws the array of vertices as individual
triangles. Each group of three vertices defines a triangle to be drawn.

Sounds familair? i m totally confused…plzzz help me out…

#2

Indexed geometry is like a lookuptable. Instead of passing the geometry data sequential (tri A, tri B, tri C, etc) you send all unique vertices to the GPU and supply an index-array with data on how to create triangles from it - tri(0,1,2), tri(0,1,3), tri(2,3,4), tri(2,3,5) etc etc.

#3

actually i am trying to draw a sphere …when i use Triangle Array , it draws perfectly…but instead of that when i tried IndexedTriangleArray…nothig comes on the screen…i m unable to find the problem…

#4

If it works with Triangle Array and you have no performance constraint, then just stick with it. If nothing is displayed it’s probably because you don’t supply an index array.
Riven explained that very well.