Black Square Shape Cover the Car - Split Second Velocity USA

[tabnk]

Black Square Shape Cover the Car. Attached Screenshots

http://i57.tinypic.com/b7j341.jpg
http://i62.tinypic.com/27y6v4.jpg

Tested on ppsspp-v1.0-75-g635f43b-windows-amd64.

[hrydgard]

Is this with "Rendering Mode" set to "Buffered Rendering"?

[thedax]

@hrydgard: Apparently this problem has existed for a while, and Buffered on/off doesn't matter:

Sunday, March 9th, 2014, 03:42 AM

"I got mine like this with the newest version of PPSPP
Even Buffered Rendering on/off,the black box won't disseapear.., Undecided
Played on Win 7 32bit"

http://forums.ppsspp.org/showthread.php?tid=1310&pid=77203#pid77203

Getting more up to date info would be useful though.

Edit: We actually have documented this issue somewhat in #4472 (comment) but the main subject of the issue is different, so let's continue the discussion here.

[tabnk]

Buffer Rendering Mode is selected and all settings are default. Thank.

http://i58.tinypic.com/23uwwa0.jpg
http://i57.tinypic.com/6f06mg.jpg

On Windows 8.1 64-bit.

[thedax]

Renamed for easier searching.

[unknownbrackets]

It seems to be the black box is caused by one of a few possible causes:

1. The game tries to copy vram to the box before rendering to it, and we don't notice. A breakpoint at 0x041dc000 with a size of at least 0x100 would answer if this is happening.
2. Blending might have a bug. It's using src * 1.0 + dst * (1.0 - src.alpha). I'm not actually sure why this would result in black, assuming that the src is rgba(0, 0, 0, 0), because that should blend fine. The preview here suggests the texture is that color:
   Split Second Velocity Colour Issue. #4472 (comment)
3. It may be somehow stencil related or related to other settings / logic op / etc. Would need to see GE debugger tabs for this.

It seems like there's a demo so I'm going to try it.

-[Unknown]

[unknownbrackets]

Okay, it does the following:

1. Renders 0x04000000 (scene) to a temporary buffer at 0x041bc00. This is used to apply bloom.
2. It clears color/alpha/stencil on 0x041dc000 (this is the black box.) Everything is cleared to 0, so it's rgba(0, 0, 0, 0) at this point.
3. It then renders the contents of it, which doesn't touch the other portions, so it should still be largely black/transparent.
4. Then it uses blending to render it. During blending, it's not using any other tests - although depth is disabled. Then blend mode is indeed as described above. The texture is RGBA, no CLUT of course.
5. The vertices have rgba(255, 255, 255, 255) colors. The texfunc is modulate, but I suppose that should keep a 0 alpha.
6. It's black right after that; it's not caused by any other rendering or upload or anything.

So, seems like a bug in blending, we may be optimizing it wrongly?

-[Unknown]

[unknownbrackets]

Okay, so using this in StateMapping.cpp:

    if (gstate.isAlphaBlendEnabled() && gstate.getBlendFuncA() == GE_SRCBLEND_FIXA && gstate.getBlendFuncB() == GE_DSTBLEND_INVSRCALPHA && gstate.getTextureAddress(0) == 0x041dc000) {
        //DebugBreak();
        glBlendFuncB = GL_ONE;
    }

Hacks it into working correctly. That means the problem child is the B func - which is GL_ONE_MINUS_SRC_ALPHA otherwise. Dual source is not being used, so I tried this trickery (along with an extra bit for the texture) in the frag shader:

    if (gstate.isAlphaBlendEnabled() && gstate.getBlendFuncA() == GE_SRCBLEND_FIXA && gstate.getBlendFuncB() == GE_DSTBLEND_INVSRCALPHA && gstate.getTextureAddress(0) == 0x041dc000) {
        WRITE(p, "  %s.a = 0.0;\n", fragColor0);
    }

This also fixes it, which means somehow we're ending up with alpha being 1.0 in the shader. It turns out that this fixes it too:

    if (gstate.isAlphaBlendEnabled() && gstate.getBlendFuncA() == GE_SRCBLEND_FIXA && gstate.getBlendFuncB() == GE_DSTBLEND_INVSRCALPHA && gstate.getTextureAddress(0) == 0x041dc000) {
        doTextureAlpha = true;
    }

So, gstate_c.textureFullAlpha is being set incorrectly somewhere.

For some reason the framebuffer is set as 565, but it's drawn as 5551 4444 so that makes no sense. Also, it is used as 4444... hmm. Oh, wait, then it draws 565 on top of that. Weird.

-[Unknown]

[unknownbrackets]

I suppose the color of the text drawn on the car may be incorrect, I think it's switching to 565 to draw maybe a shadow or something (not really sure.) Instead we are just taking the colors as they are.

-[Unknown]

[daniel229]

Yes,the text colour is not right,and there is a half circle under the car that is missing in OpenGL.

Here is the soft rendering.

[unknownbrackets]

Yeah, that requires realizing that it's been rendered to using the wrong format, and converting it on change. Unfortunately, it's going to be hard to handle that correctly without potentially making some games VERY slow unnecessarily (like Kingdom Hearts.)

Anyway, #7509 at least kills the black box. I think we should probably worry about the other glitches separately, since the game is at least playable without the black box.

-[Unknown]

[tabnk]

Will fix be release as upcoming update?

[BogdanTheGeek]

This issue can be fixed by turning on buffered rendering and running in OpenGL (DX 11 is a bit more stuttery).