[feedback] confusing Vulkan output re: samplers

[chriscamacho]

This is not a criticism, I've giving feedback on something that caused significant confusion (to my mere mortal brain) and even caused attempts to debug something that was working (as it turned out!)

from code that appears to be working just fine I see

../../../src/renderer_vk.cpp (5446): BGFX 	invalid: s_texColorSampler ((null)), r.index 655, r.count  1, r.texComponent 0, r.texDimension 0
../../../src/renderer_vk.cpp (5446): BGFX 	invalid: s_texColorTexture ((null)), r.index 655, r.count  1, r.texComponent 0, r.texDimension 0
../../../src/renderer_vk.cpp (5446): BGFX 	predefined: u_viewRect (vec4), r.index   0, r.count  1, r.texComponent 0, r.texDimension 0
../../../src/renderer_vk.cpp (5446): BGFX 	sampler: s_texColor (sampler1), r.index  64, r.count  0, r.texComponent 0, r.texDimension 2

I've concluded that this is expected as s_texColorSampler s_texColorTexture only get set when you bind the sampler (with bgfx_set_texture) is this conclusion correct ?

also it says

sampler: s_texColor (sampler1)

odd its at index 0 isn't it ?

SAMPLER2D(s_texColor, 0);

and its a sampler2D, so where did sampler1 come from and what does it actually mean ?

Its very probably I have the wrong end of the stick in more than one area, I'm only just feeling like I'm starting to get traction with bgfx, and an API doc alone doesn't really constitute full documentation - I know we'd all rather be coding, but fleshing out the details on how the library is intended to be used, what you should and shouldn't do at different points, would make the initial learning curve for new adopters significantly less steep.

For my part once I have my C only OBJ loader fully working with bgfx's C API, I intend at the very least a few more blog posts (and I hope more) and also to release this code, with an explanation of what I did and why and what gottchas I encountered along the way...

again this is not a criticism, you've obviously poured your heart and soul into the amazing renderer, but for sure the official documents could really benefit with some more fleshing out, almost a "manual" on using bgfx as it were, of course you'd have to find the extra time for this from somewhere I do appreciate that you must be pulled in multiple different directions with what to work on next in bgfx....

[bkaradzic]

sampler1 is this: https://bkaradzic.github.io/bgfx/bgfx.html#_CPPv4N4bgfx11UniformType4Enum7SamplerE

[bkaradzic]

It was previously Int1 but in rename became Sampler, but this

bgfx/src/bgfx.cpp

Line 926 in 9582f19

"sampler1",

is incorrect.

[chriscamacho]

so it should just be sampler? I was right to be confused? did I find a bug ?

[pezcode]

I've concluded that this is expected as s_texColorSampler s_texColorTexture only get set when you bind the sampler (with bgfx_set_texture) is this conclusion correct ?

Not quite, it has to do with how textures are bound to Vulkan shaders. The shaders are compiled with a separate texture + sampler, which is what the first two lines tell you about. The third mention is the actual uniform created by the user.

I would suggest to not read too much into internal log spam unless it says WARN or your app crashes 🙊

[chriscamacho]

frankly not knowing too much about Vulkan (which seem to me that you're practically writing a GPU driver just to display stuff!!! how many lines of code to open a context and render a triangle?!?) I was considering turning the debug stuff off as its caused some confusion!

I have found it interesting though to swap between different renderers (opengl/vulkan) and compare this output, it sometimes gives some intuition...

[bkaradzic]

VK renderer in bgfx has less lines of code than GL.

[chriscamacho]

I'm in awe, I'd be darn proud if I ever managed something as comprehensive as bgfx it is genuinely impressive work.