bgfx examples

[code-disaster]

Java ports of bgfx examples to accompany LWJGL/lwjgl3#240.

[httpdigest]

Let's merge this once org.lwjgl:lwjgl-bgfx is in oss.sonatype.org.

[Spasi]

The latest nightly build includes the bgfx bindings. There have been some breaking changes since this PR, e.g. bgfx_set_platform_data is now in the BGFXPlatform class.

[httpdigest]

Now, the bgfx bindings do some invalid parameter validations. The following usecase is now not possible anymore: https://github.com/bkaradzic/bgfx/blob/master/examples/02-metaballs/metaballs.cpp#L608-L610
because bgfx_alloc_transient_vertex_buffer checks the tvb via BGFXTransientVertexBuffer.validate(_tvb) which in turn checks whether DATA has been set, which it has not, because that field will be filled by the bgfx call.

Exception in thread "main" java.lang.NullPointerException
    at org.lwjgl.system.Checks.checkPointer(Checks.java:102)
    at org.lwjgl.bgfx.BGFXTransientVertexBuffer.validate(BGFXTransientVertexBuffer.java:315)
    at org.lwjgl.bgfx.BGFX.nbgfx_alloc_transient_vertex_buffer(BGFX.java:2113)
    at org.lwjgl.bgfx.BGFX.bgfx_alloc_transient_vertex_buffer(BGFX.java:2125)
    at org.lwjgl.demo.bgfx.Metaballs.frame(Metaballs.java:531)
    at org.lwjgl.demo.bgfx.Demo.run(Demo.java:160)
    at org.lwjgl.demo.bgfx.Metaballs.main(Metaballs.java:359)

[code-disaster]

Yes, this applies to bgfx_transient_index_buffer_t.data and bgfx_transient_vertex_buffer_t.data.

[Spasi]

because that field will be filled by the bgfx call

Thanks, will be fixed in the next nightly with LWJGL/lwjgl3@7808282.

[httpdigest]

Is there already a consensus on how LWJGL 3 is going to handle the bgfx shared library? Currently, when you just checkout the lwjgl3-demos repository and download all the Maven dependencies, you cannot run bgfx demos without manually building bgfx as a shared library (or downloading it from somewhere else).
I think we should handle the bgfx shared library in the same way that we handle glfw, by building it on a CI server (travis, appveyor) and include it in a natives jar.

[Spasi]

I initially thought that bgfx is statically configured for specific backends, but I was wrong. The default build is small enough and supports all backends on a given platform. So yes, I'll setup CI builds.

The builds will be configured with --with-glfw --with-shared-lib (and --with-ovr on Windows). As always, users will be able to replace the shared library with a custom build (debug, disabled backends for smaller binaries, etc).

[code-disaster]

You don't need --with-glfw. I didn't manage to compile it when I tried, and I didn't pursue it any further when I found it's not required. The integration with lwjgl-glfw is simple enough.

--with-ovr has the "disadvantage" that, for Oculus owners like me, the damn Oculus Store pops up each time I start a program which links to their SDK, no matter if I want to even use it. I'm not sure if that's a bgfx thing or just the way this works. I could unplug my Rift each time I'm coding, but for now I just opted to leave it be and compile a bgfx.dll without this flag.

In any case, it's nice that LWJGL provides the means to replace the shared lib at any time, if needed.

[httpdigest]

I also did not compile with --with-glfw, and it seems to work (on Windows).

[Spasi]

You don't need --with-glfw.

I'm afraid it's going to break badly under MacOS without --with-glfw (which is just an alias for BGFX_CONFIG_MULTITHREADED=0). Will try and let you know.

--with-ovr has the "disadvantage" that, for Oculus owners like me, the damn Oculus Store pops up each time I start a program which links to their SDK, no matter if I want to even use it.

OK, will build without it, until that issue is fixed and/or the Oculus user base increases.

[httpdigest]

I propose to add this code in Demo.java right below the GLFW window creation to fix window resizing and aspect ratio issues in all demos:

GLFWFramebufferSizeCallback fbsc;
glfwSetFramebufferSizeCallback(window, fbsc = new GLFWFramebufferSizeCallback() {
    public void invoke(long window, int width, int height) {
        Demo.this.width = width;
        Demo.this.height = height;
        bgfx_reset(width, height, Demo.this.reset);
    }
});

[LWJGL-CI]

The latest nightly build (28) includes bgfx shared libraries.

[httpdigest]

There does not seem to be bgfx natives on Maven/oss.sonatype.org.

[Spasi]

Sorry about that, should be OK now.

[httpdigest]

Yes, seems to work fine. @code-disaster, could you add the necessary changes to the pom.xml in the profiles section to include the natives, please? Then we can merge the pull request.

[httpdigest]

Thanks for your work of porting the bgfx demos!