Package org.lwjgl.opengl

Class ARBDrawElementsBaseVertex


  • public class ARBDrawElementsBaseVertex
extends java.lang.Object
    Native bindings to the ARB_draw_elements_base_vertex extension.

    This extension provides a method to specify a "base vertex offset" value which is effectively added to every vertex index that is transferred through DrawElements.

    This mechanism can be used to decouple a set of indices from the actual vertex array that it is referencing. This is useful if an application stores multiple indexed models in a single vertex array. The same index array can be used to draw the model no matter where it ends up in a larger vertex array simply by changing the base vertex value. Without this functionality, it would be necessary to rebind all the vertex attributes every time geometry is switched and this can have larger performance penalty.

    For example consider the (very contrived and simple) example of drawing two triangles to form a quad. In the typical example you have the following setup:

        vertices         indices
   ----------        -----
0 | (-1,  1) |    0 |  0  |
1 | (-1, -1) |    1 |  1  |
2 | ( 1, -1) |    2 |  2  |
3 | ( 1,  1) |    3 |  3  |
   ----------     4 |  0  |
                  5 |  2  |
                     -----

    which is normally rendered with the call

    DrawElements(TRIANGLES, 6, UNSIGNED_BYTE, &indices).

    Now consider the case where the vertices you want to draw are not at the start of a vertex array but are instead located at offset 100 into a larger array:

         vertices2         indices2
     ----------        -----
        ....        0 | 100 |
100 | (-1,  1) |    1 | 101 |
101 | (-1, -1) |    2 | 102 |
102 | ( 1, -1) |    3 | 103 |
103 | ( 1,  1) |    4 | 100 |
        ....        5 | 102 |
     ----------        -----

    The typical choices for rendering this are to rebind your vertex attributes with an additional offset of 100*stride, or to create an new array of indices (as indices2 in the example). However both rebinding vertex attributes and rebuilding index arrays can be quite costly activities.

    With the new drawing commands introduced by this extension you can instead draw using vertices2 and the new draw call:

    DrawElementsBaseVertex(TRIANGLES, 6, UNSIGNED_BYTE, &indices, 100)

    Promoted to core in OpenGL 3.2.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method and Description
      static void glDrawElementsBaseVertex(int mode, java.nio.ByteBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawElementsBaseVertex(int mode, java.nio.IntBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawElementsBaseVertex(int mode, int type, java.nio.ByteBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawElementsBaseVertex(int mode, int count, int type, long indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawElementsBaseVertex(int mode, java.nio.ShortBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawElementsInstancedBaseVertex(int mode, java.nio.ByteBuffer indices, int primcount, int basevertex)
      Renders multiple instances of a set of primitives from array data with a per-element offset.
      static void glDrawElementsInstancedBaseVertex(int mode, java.nio.IntBuffer indices, int primcount, int basevertex)
      Renders multiple instances of a set of primitives from array data with a per-element offset.
      static void glDrawElementsInstancedBaseVertex(int mode, int type, java.nio.ByteBuffer indices, int primcount, int basevertex)
      Renders multiple instances of a set of primitives from array data with a per-element offset.
      static void glDrawElementsInstancedBaseVertex(int mode, int count, int type, long indices, int primcount, int basevertex)
      Renders multiple instances of a set of primitives from array data with a per-element offset.
      static void glDrawElementsInstancedBaseVertex(int mode, java.nio.ShortBuffer indices, int primcount, int basevertex)
      Renders multiple instances of a set of primitives from array data with a per-element offset.
      static void glDrawRangeElementsBaseVertex(int mode, int start, int end, java.nio.ByteBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawRangeElementsBaseVertex(int mode, int start, int end, java.nio.IntBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawRangeElementsBaseVertex(int mode, int start, int end, int type, java.nio.ByteBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawRangeElementsBaseVertex(int mode, int start, int end, int count, int type, long indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glDrawRangeElementsBaseVertex(int mode, int start, int end, java.nio.ShortBuffer indices, int basevertex)
      Renders primitives from array data with a per-element offset.
      static void glMultiDrawElementsBaseVertex(int mode, int[] count, int type, org.lwjgl.PointerBuffer indices, int[] basevertex)
      Array version of: MultiDrawElementsBaseVertex
      static void glMultiDrawElementsBaseVertex(int mode, java.nio.IntBuffer count, int type, org.lwjgl.PointerBuffer indices, java.nio.IntBuffer basevertex)
      Renders multiple sets of primitives by specifying indices of array data elements and an offset to apply to each index.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait