Datatype and Camera Question

OpenGL Development JOGL Development
#1

Hello,
Does JOGL have a native Vertex DataType class already? (I didn’t want to use another package or make my own). Also does someone have a camera movement example using the mouse in JOGL already mocked up?

Thanks in advance,
Coop

#2

Your native vertex type is most likely going to be a FloatBuffer that was made using “allocateDirect”.
This way the memory is directly accessible to the C-side libs, therefore no copying (or minimum possible) will occur.

See other forums here and the JOGL demos for example usage.

For camera, again I recommend checking out the JOGL demos to start, specifically the Gears demo. Beyond that most any OpenGL tutorials are all you need. (Until later that is… ;-))

#3

[quote]Your native vertex type is most likely going to be a FloatBuffer that was made using “allocateDirect”.
[/quote]
I tried this way:

FloatBuffer v = ByteBuffer.allocateDirect( 3*4 ).asFloatBuffer( );
v.put( -5 ).put( -9 ).put( -9 );
gl.glVertex3fv( v.array( ) );

but receive an java.lang.UnsupportedOperationException calling that array() method.

Could you give me a clue, please?
melvyn

#4

i dont really know anything about vertex buffers. can someone just tell me what they are… like how are they different/better than just using lists of triangles. thats what im doing with my current scene graph.

about a camera. i suggest using a vector to represent the camera position and a quaternion to represent its rotation. i suggest that you read up on Quaternion math if youre unfamiliar with it… i believe there is a quat class in the javax.vecmath package, but im using my own. if you want i can paste my current Camera and Quaternion implementation in my scene graph for a physics engine. as for interpreting mouse events for rotation, there is a decent example in the Gears demo. once you understand quaternion rotations its really quite simple to implement. hope this helps.

–eric

#5

Yeah I’m still learning about quaternions, and example code would be great!

Thanks,
Coop

#6

to melvyn,
I would same just use a regular float[] for starters, special for the glVertex3fv( ) type calls.

You only need to use the FloatBuffers once you start using VertexArray type rendering.

Sounds like you are have a bit of OpenGL API fun. I would suggest checking out the NeHe tutorials as well as a good OpenGL book to get you started with JOGL.

#7

Sorry, it seems that my question was not accurate enough. My example really is not very useful indeed.
What I wanted to know was why FloatBuffer.toarray( ) throws that exception (although we dont need it since the relevant vertex array methods get a java.nio.Buffer).

#8

array() is an optional method. I’m not sure you’ll get much of a better answer than what the javadocs say: