Fixing color order for RGB10A2 on vulkan.

[mtytel]

Not sure why this was flipped but this fixes RGB10A2 frame buffer colors on vulkan.

[bkaradzic]

What is wrong with it?

[mtytel]

Hmm, ok that example is correct.
But if I change the RGBA32F frame buffers in the 38-bloom example to RGB10A2 format. R and B are flipped.
RGBA32F:

RGB10A2:

[mtytel]

OK, now this change seems to make both work.

[mtytel]

@bwrsandman Sorry for the ping but I saw you've touched this format/swizzle code before. You mind taking a look?
It looks like the color was only flipped when creating a framebuffer and not a texture and this change makes both work.

[bwrsandman]

I can have a look over the weekend.
What's missing from the 47-pixel format example to repro the bug?

[mtytel]

Thanks!
The bug is when creating frame buffers with createFrameBuffer and 47-pixelformats uses createTexture2D so it works fine there.

To reproduce the bug change this line

bgfx/examples/38-bloom/bloom.cpp

Line 398 in b927871

, bgfx::TextureFormat::RGBA32F

to use RGB10A2 instead and the colors will change like above (flipping R and B)

[bkaradzic]

@mtytel

The bug is when creating frame buffers with createFrameBuffer and 47-pixelformats uses createTexture2D so it works fine there.

That's wrong diagnosis... bgfx::createFrameBuffer is just calling bgfx::createTexture2D internally:

bgfx/src/bgfx.cpp

Lines 5078 to 5083 in b927871

	FrameBufferHandle createFrameBuffer(uint16_t _width, uint16_t _height, TextureFormat::Enum _format, uint64_t _textureFlags)
	{
	_textureFlags |= _textureFlags&BGFX_TEXTURE_RT_MSAA_MASK ? 0 : BGFX_TEXTURE_RT;
	TextureHandle th = createTexture2D(_width, _height, false, 1, _format, _textureFlags);
	return createFrameBuffer(1, &th, true);
	}

[mtytel]

I'm not saying there's something wrong with createFrameBuffer. I just mean currently the colors are flipped when using a frame buffer with that format and not when using a texture.