// aaaarrgghhh!!!  meshes are horrible!!!
struct spheredef
{
	LPDIRECT3DVERTEXBUFFER9 vb;
	LPDIRECT3DINDEXBUFFER9 ib;

	int numverts;
	int numindexes;
};

spheredef sd_Jupiter;
spheredef sd_Sattelite;


HRESULT D3D_BuildSphere (spheredef *sd, int slices, int stacks, float radius)
{
	HRESULT hr = S_OK;

	// prevent overflowing the index buffer
	while (slices * stacks * 6 > 65534)
	{
		slices--;
		stacks--;
	}

	float drho = D3DX_PI / (float) stacks;
	float dtheta = (D3DX_PI / (float) slices) * 2.0f;

	float ds = 1.0f / (float) slices;
	float dt = 1.0f / (float) stacks;

	float t = 1.0f;
	float s = 0.0f;

	hr = d3d_Device->CreateVertexBuffer
	(
		sizeof (float) * 8 * stacks * (slices + 1) * 2,
		0,
		0,
		D3DPOOL_MANAGED,
		&sd->vb,
		NULL
	);

	if (FAILED (hr)) return hr;

	hr = d3d_Device->CreateIndexBuffer
	(
		sizeof (unsigned short) * slices * stacks * 6,
		0,
		D3DFMT_INDEX16,
		D3DPOOL_MANAGED,
		&sd->ib,
		NULL
	);

	if (FAILED (hr)) return hr;

	float *sv = NULL;
	unsigned short *ndx = NULL;

	sd->vb->Lock (0, 0, (void **) &sv, 0);
	sd->ib->Lock (0, 0, (void **) &ndx, 0);

	sd->numindexes = 0;
	sd->numverts = 0;

	int stripverts = (slices + 1) * 2;

	for (int i = 0; i < stacks; i++, t -= dt, sd->numverts += stripverts)
	{
		float rho = (float) i * drho;
		float srho = (float) (sin (rho));
		float crho = (float) (cos (rho));
		float srhodrho = (float) (sin (rho + drho));
		float crhodrho = (float) (cos (rho + drho));

		s = 0.0f;

		// each of these is a triangle strip
		for (int j = 0; j <= slices; j++, s += ds, sv += 16)
		{
			float theta = (j == slices) ? 0.0f : j * dtheta;
			float stheta = (float) (-sin (theta));
			float ctheta = (float) (cos (theta));

			sv[0] = stheta * srho * radius;
			sv[1] = ctheta * srho * radius;
			sv[2] = crho * radius;

			sv[3] = stheta * srho;
			sv[4] = ctheta * srho;
			sv[5] = crho;

			VectorNormalize (&sv[3]);

			sv[6] = s;
			sv[7] = t;

			sv[8] = stheta * srhodrho * radius;
			sv[9] = ctheta * srhodrho * radius;
			sv[10] = crhodrho * radius;

			sv[11] = stheta * srhodrho;
			sv[12] = ctheta * srhodrho;
			sv[13] = crhodrho;

			VectorNormalize (&sv[3]);

			sv[14] = s;
			sv[15] = (t - dt);
		}

		// and unwind the strip into it's component indexes
		for (int j = 2; j < stripverts; j++, ndx += 3, sd->numindexes += 3)
		{
			ndx[0] = sd->numverts + j - 2;

			if (j & 1)
			{
				ndx[1] = sd->numverts + j;
				ndx[2] = sd->numverts + j - 1;
			}
			else
			{
				ndx[1] = sd->numverts + j - 1;
				ndx[2] = sd->numverts + j;
			}
		}
	}

	sd->vb->Unlock ();
	sd->ib->Unlock ();

	return S_OK;
}


void D3D_DestroySphere (spheredef *sd)
{
	if (sd->ib)
	{
		sd->ib->Release ();
		sd->ib = NULL;
	}

	if (sd->vb)
	{
		sd->vb->Release ();
		sd->vb = NULL;
	}
}