Implement basic depth texturing for OpenGL #14042

hrydgard · 2021-01-31T22:53:47Z

Dug up a couple of old branches and put them together and got it working.

Only works on desktop, this currently requires GL_ARB_depth_clamp which is not really supported on mobile (there is an extension, GL_EXT_depth_clamp, but few mobile devices support it).

Need to figure out what to do about the extended Z mappings we use when either extension is not available.

Helps #6411 for OpenGL on desktop primarily, and certain other games affected by #13256
are likely working too like the fog in Harry Potter.

Let's merge after 1.11.

Panderner · 2021-01-31T23:16:48Z

What required OpenGL version to support GL_DEPTH_CLAMP?

hrydgard · 2021-01-31T23:25:30Z

I believe desktop GL 3.2 or newer is enough, or that exposes the extention GL_ARB_depth_clamp .

unknownbrackets

In the case where we enable this, shouldn't we also enable accurate depth? Otherwise the depth values we're texturing from will be skewed and wrong in some cases.

-[Unknown]

unknownbrackets · 2021-02-01T00:41:59Z

Common/GPU/OpenGL/thin3d_gl.cpp

+	caps_.depthClampSupported = gl_extensions.ARB_depth_clamp;
+
+	// Interesting potential hack for emulating GL_DEPTH_CLAMP (use a separate varying, force depth in fragment shader):
+	// https://stackoverflow.com/questions/5960757/how-to-emulate-gl-depth-clamp-nv


We probably should do this, but I'd think we might need a setting - it might make things a lot slower in some games where people might be willing to withstand weird clipping issues near the edges for speed...

In some games depending on how they draw, it might not be that big a difference I suppose.

-[Unknown]

Yeah, will depend a lot on the GPU architectures too, changing gl_FragDepth can have between nearly none to a very large performance penalty, I believe. So a blanket enable is probably not realistic, adding that to the comment.

GPU/GLES/StateMappingGLES.cpp

unknownbrackets · 2021-02-01T00:59:51Z

GPU/Common/DepalettizeShaderCommon.cpp

+
+		if (pixelFormat == GE_FORMAT_DEPTH16) {
+			DepthScaleFactors factors = GetDepthScaleFactors();
+			WRITE(p, "const float z_scale = %f;\n", factors.scale);


In this case, I'd recommend factors.scale * 1.0f / 65535.0f. Then below it'd just be color = (color - z_offset) * z_scale; right?

These values wouldn't vary, so we could avoid the formula when offset is 0 and scale is 65535, which will be true if clamp is enabled.

-[Unknown]

Hm, I don't see how dividing by 65535 helps here. Then we'd just have to scale it up again to turn it into an integer index later...

Indeed, the values are constant, but I'm thinking that we might be able to also support this when we use the depth rescaling/offset stuff to simulate clamping, in some cases, so want to keep the flexibility. The distortion you mentioned earlier kind of prevents that though I guess.

Oh, I missed the other code below that wants it as an int. This doesn't already work with the 1/4 scale thing?

Also in that case, how does WRITE(p, " float color = tex.Sample(texSamp, v_texcoord0).x;\n"); work with color.x later?

-[Unknown]

I'm not sure honestly if it works correctly with the 1/4 scale. But hopefully it does.

You can take .x of a float in HLSL, it's effectively a vec1. However it does look confusing...

Panderner · 2021-02-01T03:28:16Z

Any android devices that supports GL_EXT_depth_clamp?

brujo5 · 2021-02-01T04:33:56Z

@Panderner Maybe the nvidia shield android tv

glebm · 2021-02-01T22:10:38Z

I think many mali GPUs support GL_EXT_depth_clamp

hrydgard · 2021-02-01T22:15:09Z

Not according to gpuinfo: http://opengles.gpuinfo.org/listreports.php?extension=GL_EXT_depth_clamp

ghost · 2021-06-08T07:36:23Z

@hrydgard This pr only help desktop opengl but not android without GL_EXT_depth_clamp?

Should make support for depth texturing quite easy. Unfortunately, this extension does not exist on OpenGL ES. There we'll have to use ugly tricks with gl_FragDepth if we want this.

…now. Need to figure out what to do about other Z mappings. Helps #6411 for OpenGL on desktop primarily, and certain other games affected by #13256 are likely working too like the fog in Harry Potter.

hrydgard · 2021-07-09T19:12:55Z

Rebased on master again, surprisingly no conflicts.

And no, this won't help on GLES unfortunately, only desktop-gl for now.

And in response to a previous comment, this does enable accurate-depth when the required extension is available, so the depth buffer scaling issues and such should not apply.

I do think this might be ready for merge as-is.

hrydgard · 2021-07-09T20:50:48Z

Eh, let's just try it.

unknownbrackets · 2021-07-17T20:52:17Z

GPU/GLES/TextureCacheGLES.cpp

 	if (!gstate_c.Supports(GPU_SUPPORTS_32BIT_INT_FSHADER)) {
 		useShaderDepal = false;
+		depth = false;  // Can't support this


Hm, is it better to use the color part of the framebuf or just ignore the attachment I wonder?

-[Unknown]

The color part probably isn't usually very meaningful when you're trying to read the depth, so ignoring is probably better... unfortunately currently no good way to bind an empty texture here? Hm.

I guess the better thing would be a Supports flag and handle this when choosing candidates... (maybe we already even do that?)

-[Unknown]

Yeah, I think we already do...

Panderner · 2021-09-13T02:56:42Z

Note: This also fixes Hokuto no Ken blackscreen issue for OpenGL for desktop systems (#7932).

unknownbrackets · 2021-09-13T03:27:56Z

That's just because it enables depth clamp on desktop OpenGL. Accurate depth (with its "simulation" of depth clamp) would probably fix it, too.

-[Unknown]

hrydgard added GE emulation Backend-independent GPU issues Depth Texture An effect needs texturing from depth buffers. labels Jan 31, 2021

hrydgard added this to the v1.12.0 milestone Jan 31, 2021

unknownbrackets reviewed Feb 1, 2021

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mirh mentioned this pull request Apr 8, 2021

VertexShaderGen: Sonic epsilon hack for OpenGL ES dolphin-emu/dolphin#9591

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ghost mentioned this pull request Jun 1, 2021

Silent hill zero part of the body disappear #8497

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hrydgard added 5 commits July 9, 2021 21:09

Support depth clamping in OpenGL where available.

df6abe8

Should make support for depth texturing quite easy. Unfortunately, this extension does not exist on OpenGL ES. There we'll have to use ugly tricks with gl_FragDepth if we want this.

Implement basic depth texturing for OpenGL, requires depth clamp for …

4e8ffae

…now. Need to figure out what to do about other Z mappings. Helps #6411 for OpenGL on desktop primarily, and certain other games affected by #13256 are likely working too like the fog in Harry Potter.

Android buildfix

cde3889

Address feedback

4c9b5ad

HLSL depal simplification

90460df

hrydgard force-pushed the depth-texturing-gl branch from 253f354 to 90460df Compare July 9, 2021 19:12

hrydgard merged commit 1f16edd into master Jul 9, 2021

hrydgard deleted the depth-texturing-gl branch July 9, 2021 20:50

Panderner mentioned this pull request Jul 10, 2021

Me and My Katamari Visual Bug Background #6411

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Implement basic depth texturing for OpenGL #14042

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Implement basic depth texturing for OpenGL #14042

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