Going Native with the NDK - Beginning Android Games - page 641

public void setVertices( float[] vertices, int offset, int length) {
this .vertices.clear();
JniUtils.copy( this .vertices, vertices, offset, length);
this .vertices.position(length * 4);
}
public void bind() {
GL10 gl = glGraphics.getGL();
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
vertices.position(0);
gl.glVertexPointer(3, GL10.GL_FLOAT, vertexSize, vertices);
if (hasColor) {
gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
vertices.position(12);
gl.glColorPointer(4, GL10.GL_FLOAT, vertexSize, vertices);
}
if (hasTexCoords) {
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
vertices.position(hasColor ? 28 : 12);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, vertexSize, vertices);
}
if (hasNormals) {
gl.glEnableClientState(GL10.GL_NORMAL_ARRAY);
int offset = 12;
if (hasColor)
offset += 16;
if (hasTexCoords)
offset += 8;
vertices.position(offset);
gl.glNormalPointer(GL10.GL_FLOAT, vertexSize, vertices);
}
}
// rest as before
The big changes are in setVertices() and bind() . In setVertices() , we now use the JniUtils
class to copy the float[] array to the direct ByteBuffer instance. Note that we set the limit and
position of the buffer manually. This is necessary because our JNI method doesn't manipulate
the position and limit fields of the buffer. The OpenGL ES methods we pass that buffer to
might use that information, though.
In bind() , we have to modify the position offsets because we are now counting in bytes instead
of ints.
Note If you paid attention, you can see that we could do the same for the indices ByteBuffer .
This would require adding a new native method to JniUtils that takes a short array. Give it a try!