Awesome, thanks for the code sample. I'll admit I am reluctant to use something like that. It does indeed seem very hackish, although it is difficult to argue with results. I'll work on something that combines each chunk into a single or low number of objects and compare to see which one of these solutions comes out ahead.

Chunks would need to be redrawn and recompiled each time a chunk loads next to them or a block in the chunk changes. Is it expensive to recreate an object with ~3000 triangles? Only the chunk the player is in would ever need to be recreated in this manner.

I have to think a similar thing needs to be accomplished whether the rendering is accomplished through JPCT or just OpenGL. A chunk is made up of display lists at some point, whether that is

each chunk is 6 display lists, one for each tile side
each chunk tile is its own display list
every chunk tile is in a single display list

There must be a good middle ground that makes sense.

---

Thinking on the idea you posted, it does seem very hackish. Basically what that says to me is that it's more performant to leave vertices in the world vs. recompiling the object that contains them. If so, would it be less hackish to simply leave the tile face in, but change it to be completely transparent if it no longer needs to be rendered?

I'm procedurally generating a world with a very blocky shape (think Minecraft or Infiniminer). The performance issues I'm pretty sure come from too many Object3Ds in the scene. Even with a small chunk of terrain like a single 16x16x16 chunk, there are 1536 tiles to render, assuming you cut out the interior faces. As more chunks get added, say even a tiny playable area like 6 chunks, it potentially gets into the couple thousand range of tiles, each its own Object3D. What makes sense from a design perspective (each face represented by an individual plane) doesn't seem to work when rendered in large numbers. If this sounds familiar it's because I made a post on this same issue almost a year ago.

Correct me if I'm wrong but my thinking is that tiles in a chunk need to be merged and recompiled so instead of 1536 Object3Ds you have one. Rendering 6 chunks isn't 5000 Object3Ds but 6. When I look at some of the other demos, which all render with great framerates, the main difference I notice is that while objects might have a lot of triangles within them, they are still just one contained Object3D. There clearly seems to be a disadvantage to rendering too many discrete objects in a scene. And since you can then compile the Object3D, you've got the entire chunk, all ~1000 faces of it, on a single display list (or VBO).

Edit: I feel like an idiot when I post on this subject. I spend a lot of timing writing web application code and then I try to render a simple graphics scene and I'm really out of my element. Perhaps that's what draws me to this time and time again.

I have a prototype I've been working on, which I originally started in OpenGL and am trying to port over to JPCT. The majority of this transfer was quite painless - JPCT is way easier to use than base OpenGL calls, and I can only see the benefits getting larger as the project progresses. However, I've not yet been able to get the same performance as the OpenGL solution. This morning I was thinking that a big part of the problem is I don't exactly know what some of these Object3D functions do behind the scenes.

From a high level, I view an Object3D as a set of triangles that, when added to a World, will be rendered. But that's perhaps not even accurate, and there's also several functions that need to be called that are in a lot ways very black-box in their description.

Here are the functions I'm curious about:

Quote
public void build()
Initializes some basic object properties that are needed for almost all further processing. build() should be called if the object is "ready to render" (loaded, Textures assigned, placed, rendering modes set...).
Adding new triangles to an object after calling build() may work but doesn't have to. If you want to do this, call unbuild() before.

Based on this description this tells me an Object3D is initially in a state that is not renderable. At a high level what does build do to make it renderable?

Quote
public void compile()
Compiles an Object3D. Don't confuse this with build(), which does something completely different. A compiled object can be rendered faster when using the hardware renderer but has some shortcomings...

Based on the Javadoc I'm assuming this sets up the Object3D in a display list or VBO (depending on settings).

That worked. Thank you.

A decent guess, but it's not visible from any angle. Camera is in fly mode and I have checked it from below, above, left, right, etc.

Is there any reason I shouldn't do:


Object3D plane1 = Primitives.getPlane(1, 10f);
Object3D plane2 = Primitives.getPlane(1, 10f);
plane2.rotateX((float) Math.toRadians(90));

Object3D merged = Object3D.mergeObjects(plane1, plane2);
world.addObject(merged);
world.buildAllObjects();


When I do so only one plane is visible.

I solved this by eliminating all shared faces. I had assumed that overdrawing between the chunks wouldn't be a big deal but that proved false. Thanks for all your help.

An important thing I should note is that the planes *between* chunks, the ones on the chunk edge, are always rendered. This was a design decision to allow chunks to be wholly separate entities. Each chunk does not know the contents of its neighbors and thus assumes it must render its outside faces. After this latest test I don't know if that design decision is going to hold up.

Screenshot of what I'm rendering:



Log output:


run:
Java version is: 1.6.0_20
-> support for BufferedImage
Version helper for 1.5+ initialized!
-> using BufferedImage
Software renderer (OpenGL mode) initialized
Software renderer disposed
Current mode:800 x 600 x 32 @75Hz
Driver is: atiu9p64 aticfx64 aticfx64 atiu9pag aticfx32 aticfx32 atiumd64 atidxx64 atidxx64 atiumdag atidxx32 atidxx32 atiumdva atiumd6a atitmm64/null on ATI Technologies Inc. / ATI Radeon HD 4800 Series
GL_ARB_texture_env_combine supported and used!
FBO supported and used!
OpenGL renderer initialized (using 4 texture stages)
Loading Texture...res/grid.jpg
created new chunk
created new chunk
created new chunk
created new chunk
created new chunk
created new chunk
created new chunk
created new chunk
created new chunk
Compiling source object...
Subobject of object 1/object3 compiled using 2 vertices in 0ms!
Object 1/object3 compiled to 1 subobjects in 4ms!
Object 3/object5 precompiled!
Object 5/object7 precompiled!
Object 7/object9 precompiled!
Object 9/object11 precompiled!
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... this goes on for awhile! Had to truncate it because the forum software wouldn't let me put this many characters in one post.


The class which creates the planes does so with methods like this:


private static void initModel() {
        if(MODEL == null) {
            MODEL = Primitives.getPlane(1, 1);
            MODEL.build();
            MODEL.compile();
        }
    }

public void drawTop() {
        renderable = true;

        Object3D plane = new Object3D(MODEL, true);
        plane.rotateX((float)Math.toRadians(90));
        plane.translate(position.x, position.y-0.5f, position.z);
        //plane.setCollisionMode(Object3D.COLLISION_CHECK_OTHERS);
        plane.setTexture("grid");
        plane.build();
        plane.shareCompiledData(MODEL);
        plane.compile();
        planes.add(plane);
    }
public Object3D[] getObjects() {
        return planes.toArray(new Object3D[0]);
    }


In that screenshot I made 38 chunks 4*4*4 which is ((4*4)*6 ) * 38 = 3648 planes/quads/faces. Within each chunk there are no inner faces being created. There's nothing else in the scene. You can see the FPS I'm achieving there (obviously FRAPS kills this a bit).

I'm not running any Config flags, just using default settings. Renderer is:

FrameBuffer buffer = new FrameBuffer(800, 600, FrameBuffer.SAMPLINGMODE_HARDWARE_ONLY);
buffer.disableRenderer(IRenderer.RENDERER_SOFTWARE);
buffer.enableRenderer(IRenderer.RENDERER_OPENGL, IRenderer.MODE_OPENGL);

Yeah, that's pretty conclusive. There's something I could/should be doing to my plane creation to make it render faster... I assume the same compile, clone steps as above? I will do a thorough test of those techniques tonight.

Given the results we've gotten so far I went ahead and came up with an algorithm that generates a "chunk" of 8x8x8 cubes with no inner faces. I say "cube" but each part of the overall chunk is no longer a cube persay, but an object that is capable of creating only the faces (which are planes) that it's instructed to. So an inner cube has no faces at all where an outside one has 1-3.

Previously I was creating (8^3)*6 faces = 3,072 faces for a chunk of this size. Now it's (8*2)*6 = 96. However, after plugging this back into my dynamic terrain generation and generating about 15 chunks I was disappointed to find the FPS dropping quickly. 15 chunks is about 1,440 planes, half of which are back culled, which I would assume can be rendered quite easily. My computer isn't too old.... Core 2 Duo @ 3.0 GHz, 4 GB RAM, modern graphics card, but I get about 30 FPS.

Are these results typical? I tried reusing the same plane and compiling it like we discussed above, but the results were similar.

Edit: I want to thank you again for looking into these issues. I'm a professional developer but don't have a lot of experience (yet) with graphics. It really is a whole new set of challenges.

Very comprehensive analysis. I've gone back to my OpenGL test case and perhaps I had some confirmation bias going on at the time because the performance isn't as good as I stated previously. I wasn't running an FPS monitor and it just felt smoother, but the numbers don't lie. It's a little better, but not significantly. After doing the adjustments you've laid out the performance is pretty similar to JPCT, so thanks for that advice.

Is there any culling I could implement to have the renderer ignore the cubes that are clearly not visible? In the case I sent you most of those cubes are completely obscured by the ones on top/in front of them. I'll look into what I can do, but I'm also curious if you have any suggestions.

Sent a simple test case to hostmaster@jpct.net


Java version is: 1.6.0_20
-> support for BufferedImage
Version helper for 1.5+ initialized!
-> using BufferedImage
Software renderer (OpenGL mode) initialized
Software renderer disposed
Current mode:800 x 600 x 32 @75Hz
Driver is: atiu9p64 aticfx64 aticfx64 atiu9pag aticfx32 aticfx32 atiumd64 atidxx64 atidxx64 atiumdag atidxx32 atidxx32 atiumdva atiumd6a atitmm64/null on ATI Technologies Inc. / ATI Radeon HD 4800 Series
GL_ARB_texture_env_combine supported and used!
FBO supported and used!
OpenGL renderer initialized (using 4 texture stages)
Loading Texture...res/rock.jpg
Loading Texture...res/sky.gif
Loading Texture...res/sky2.gif
Software renderer disposed
Hardware supports textures up to 8192*8192 in size!
OpenGL renderer disposed