fix: Always vflip cubemaps #7

sshcrack · 2025-07-27T21:06:27Z

Fixes #6 (not sure if it breaks other cubemaps)

dtcxzyw

[
    {
        "inputs": [
            {
                "id": "4dX3Rr",
                "filepath": "/media/a//media/previz/cubemap00.png",
                "previewfilepath": "/media/ap//media/previz/cubemap00.png",
                "type": "cubemap",
                "channel": 0,
                "sampler": {
                    "filter": "mipmap",
                    "wrap": "clamp",
                    "vflip": "true",
                    "srgb": "false",
                    "internal": "byte"
                },
                "published": 1
            }
        ],
        "outputs": [
            {
                "id": "4dfGRr",
                "channel": 0
            }
        ],
        "code": "#define rot(a) mat2( sin(a+vec4(0,33,11,0)) )  // https://www.shadertoy.com/view/XlsyWX\n\n#define F0 vec3( 1 , 1.- 2.*(U/R).yx )                 // to index each face map\n#define F1 vec3( 2.*(U/R).x -1. , 1 , 2.*(U/R).y -1. )\n#define F2 vec3( 2.*(U/R).x -1. , 1.- 2.*(U/R).y , 1 )\n\nvoid mainImage( out vec4 O, in vec2 U )\n{\n    vec2 R = iResolution.xy;\n    float FOV = .5;\n    vec3 D = normalize( vec3( 1./FOV, (U+U-R)/R.y ) ); // ray direction\n//  Note that D see faceID 0, -D see faceID 3\n//            D.zxy    \"   1, -D.zxy   \"    4 \n//            D.yzx    \"   2, -D.yzx   \"    5\n//  see F0,F1,F2 for accurate indexing of face maps.\n    \n    D.xz *= rot(iTime/2.);\n    D.yz *= rot(iTime/2.);               \n   \n    O = texture( iChannel0, D );\n}",
        "name": "Image",
        "description": "",
        "type": "image"
    },
    {
        "inputs": [],
        "outputs": [
            {
                "id": "4dXGR8",
                "channel": 0
            }
        ],
        "code": "#define hue(v)  ( .6 + .6 * cos( 6.3*(v)  + vec4(0,23,21,0)  ) ) // https://www.shadertoy.com/view/ll2cDc\n\nvoid mainCubemap( out vec4 O, vec2 U, vec3 C, vec3 D ) // note that C==vec3(0)\n    //           out Color, MapCoord, Center(=0), rayDir\n{\n    // --- part specific to each of the 6 faces\n    \n    vec3 A = abs(D); // seek for max direction: i = invmax(abs(D[i]))\n    int i=0; \n    float      M = A.x; \n    if (A.y>M) M = A.y, i=1;\n    if (A.z>M) M = A.z, i=2;\n    int  faceID = i + 3* int(D[i]<0.);\n    \n    O = hue(float(faceID)/6.);\n    \n    \n    // --- part indentical on the 6 faces\n    \n    vec2 R = iResolution.xy; // always 1024\n    U = ( U+U - R ) / R.y;\n    O *= vec4( .8+.2*sin(34.*length(U)) );\n}\n",
        "name": "Cube A",
        "description": "",
        "type": "cubemap"
    }
]

The input channel ID does not necessarily equal the output channel ID.
Can you tell what Shadertoy does in this case? Does cubemap00.png mean cube A?

shadertoy/NodeEditor/PipelineEditor.cpp

Co-authored-by: Yingwei Zheng <[email protected]>

sshcrack · 2025-07-29T10:32:46Z

I found this piece of code:

function assetID_to_cubemapBuferID( id )
{
    if( id==='4dX3Rr' ) return 0;
    return -1;
}
// ...
if( assetID_to_cubemapBuferID(url.mID)!==-1 )
        {
            texture.mImage = new Image();
            texture.mImage.onload = function()
            {
                texture.loaded = true;
                if( me.mTextureCallbackFun!==null )
                    me.mTextureCallbackFun( me.mTextureCallbackObj, slot, texture.mImage, true, 2, 1, -1.0, me.mID );
            }
            texture.mImage.src = "/media/previz/cubemap00.png";

            this.mEffect.ResizeCubemapBuffer(0, 1024, 1024 );

        }
        else
        {
            texture.image = [ new Image(), new Image(), new Image(), new Image(), new Image(), new Image() ];

            let numLoaded = 0;
            for (var i=0; i<6; i++ )
            {
                texture.image[i].mId = i;
                texture.image[i].crossOrigin = '';
                texture.image[i].onload = function()
                {
                    var id = this.mId;
                    numLoaded++;
                    if( numLoaded===6 )
                    {
                        texture.globject = renderer.CreateTextureFromImage(renderer.TEXTYPE.CUBEMAP, texture.image, renderer.TEXFMT.C4I8, rti.mFilter, rti.mWrap, rti.mVFlip);
                        texture.loaded = true;
                        if (me.mTextureCallbackFun !== null)
                            me.mTextureCallbackFun(me.mTextureCallbackObj, slot, texture.image[0], true, 2, 1, -1.0, me.mID);
                    }
                }

                if( i === 0) 
                {
                    texture.image[i].src = url.mSrc;
                } 
                else 
                {
                    let n = url.mSrc.lastIndexOf(".");
                    texture.image[i].src = url.mSrc.substring(0, n) + "_" + i + url.mSrc.substring(n, url.mSrc.length);
                }
            }
        }

sshcrack · 2025-07-29T10:44:03Z

Actually, this turns out to be much simpler, let me update (I'll use clang format before this is merged because handling two different codebases (one headless the other one with ui) is quite stressful

dtcxzyw · 2025-07-29T14:58:12Z

shadertoy/NodeEditor/PipelineEditor.cpp

    };
    std::unordered_set<std::string> passIds;
+    // Look at any index.html at EffectPass.prototype.NewTexture if(assetID_to_cubemapBuferId)
    const auto isDynamicCubeMap = [&](nlohmann::json& tex) {


No, this is just a comment why I've changed it like the way I did (for a few other shaders including https://www.shadertoy.com/view/Xlcczj)

function assetID_to_cubemapBuferID( id ) { if( id==='4dX3Rr' ) return 0; return -1; }

This method just checks if it is a dynamic cube map as far as my understanding goes

/home/runner/work/shadertoy/shadertoy/shadertoy/NodeEditor/PipelineEditor.cpp:1677:20: error: ‘dynamicCubeMap’ was not declared in this scope; did you mean ‘isDynamicCubeMap’?
1677 | if(dynamicCubeMap) {
| ^~~~~~~~~~~~~~
| isDynamicCubeMap

sshcrack · 2025-07-29T15:49:25Z

I'm very close to a fix I think but I'm still facing this issue and I just can't solve it:

I'm using this shadertoy to debug: https://www.shadertoy.com/view/t3cSRl

Right now with my implementation (currently at https://github.com/sshcrack/shadertoy-headless using the debug-window preset)
the sphere turns out to be this:

Do you happen to know why?

dtcxzyw · 2025-07-29T18:28:24Z

Looks like the order of the 6 textures is incorrect, or some faces need to be flipped.

dtcxzyw · 2025-07-30T13:44:07Z

I'm using this shadertoy to debug: https://www.shadertoy.com/view/t3cSRl

I disabled the VFlip flag on the iChannel0, and nothing happened. Should we always flip the Y coordinate of vertices for cubemap render targets?

sshcrack · 2025-07-30T14:04:20Z

Yeah, this is a bug in the codebase of shadertoy. I've decided to make read the vflip property of the input. If the shadertoy dev decides to fix that bug, we don't need to adjust the code anymore
Every shadertoy I saw with cubemaps had the vflip property enabled, I think the only way to disable vflip is by doing custom POST requests

sshcrack · 2025-07-30T14:08:35Z

I've disabled the vflip property using the custom request method but it seems like this doesn't affect the renderer
See
https://www.shadertoy.com/view/t3cSRl
and
https://www.shadertoy.com/view/WXcSzs

dtcxzyw · 2025-07-30T14:21:39Z

shadertoy/OpenGL.cpp

+
+                // For Y-flipped cubemaps, also flip Y coordinates of all faces
+                // to match ShaderToy's UNPACK_FLIP_Y_WEBGL behavior
+                if(mType == NodeType::CubeMapFlippedY) {


I commented out the Y-flipping logic and ~~the result is correct~~:

I think the changes to cube vertex indices are enough.

This is so the cubemaps are actually flipped.
This is how the output should look like:

(Notice that the red color is on the top left instead of bottom left)

sshcrack · 2025-07-30T14:28:36Z

The changes to vertices broke the voxel shader: https://www.shadertoy.com/view/ssf3zH, I don't know how to fix this yet.
This is weird because the shader doesn't even use CubeMaps. Is this bug occurring because of a previous commit?

dtcxzyw · 2025-07-30T14:44:56Z

The changes to vertices broke the voxel shader: https://www.shadertoy.com/view/ssf3zH, I don't know how to fix this yet. This is weird because the shader doesn't even use CubeMaps. Is this bug occurring because of a previous commit?

It works on my side (NVIDIA RTX 4060 Laptop).

sshcrack · 2025-07-30T14:48:29Z

Oh sorry, didn't check out to this codebase, works for me as well. I've got this bug at shadertoy-headless

dtcxzyw · 2025-07-30T14:52:48Z

Yeah, this is a bug in the codebase of shadertoy. I've decided to make read the vflip property of the input. If the shadertoy dev decides to fix that bug, we don't need to adjust the code anymore
Every shadertoy I saw with cubemaps had the vflip property enabled, I think the only way to disable vflip is by doing custom POST requests

I don‘t like to add a new node type for this workaround. Just flip Y for all cubemaps.

sshcrack · 2025-07-30T14:58:00Z

Okay, will do

fix(render): Fix grayscale volumes (dtcxzyw#8)

(cherry picked from commit 5506388)

dtcxzyw

LGTM.

sshcrack added 2 commits July 27, 2025 23:05

fix: Use other method to identify dynamic cube maps

a1bc2ab

Update PipelineEditor.cpp

6d04c7e

dtcxzyw reviewed Jul 28, 2025

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shadertoy/NodeEditor/PipelineEditor.cpp Outdated Show resolved Hide resolved

Update shadertoy/NodeEditor/PipelineEditor.cpp

dd3fd6d

Co-authored-by: Yingwei Zheng <[email protected]>

sshcrack added 2 commits July 29, 2025 12:44

Update PipelineEditor.cpp

4faf9e0

Update PipelineEditor.cpp

949bd8e

dtcxzyw reviewed Jul 29, 2025

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sshcrack added 2 commits July 30, 2025 14:47

Add new CubeMapFlippedY type & fix vertex indicies

18a40d6

Add GUI specific code

b091c03

sshcrack marked this pull request as ready for review July 30, 2025 12:50

dtcxzyw reviewed Jul 30, 2025

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sshcrack added 2 commits July 30, 2025 17:02

Merge pull request #2 from dtcxzyw/main

4113766

fix(render): Fix grayscale volumes (dtcxzyw#8)

refactor: Always flip vertical for cubemaps

bdaa1cb

(cherry picked from commit 5506388)

sshcrack changed the title ~~fix: Use other method to identify dynamic cube maps~~ fix: Always vflip cubemaps Jul 30, 2025

dtcxzyw approved these changes Jul 30, 2025

View reviewed changes

dtcxzyw merged commit 7192f6d into dtcxzyw:main Jul 30, 2025
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fix: Always vflip cubemaps #7

fix: Always vflip cubemaps #7

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