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<p class="MsoNormal">All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Since my grand scheme of doing #define inserts was unreasonable. I’ve slept on it, and I’m planning to do the following.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Once I’ve finished revising the Material/Shader section of the exporter code, I’m going to make an X3D test file that has three versions of the damaged helmet in it, each with either a PhysicalMaterial node or an X3D shader node of some
type, all generated from a Maya MaterialXSurfaceShader node.<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo7">One that has an X3D PhysicalMaterial node with X_ITE extensions.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo7">One that has an X3D PackagedShader node with a reference to a MaterialX “document#shader” in its URL field, and an appropriate set of fields based on what would ordinarily be considered
to be public uniform variables.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo7">One that has an X3D ComposedShader node with an appropriate set of ShaderPart nodes with the corresponding *<b>.vert/</b>*frag files in the ShaderPart URL fields. The CompsedShader
will have an appropriate set of fields based on the Public uniform variables found in the vert/frag files. This node will assume that a browser’s built-in uniform and input variables are the same as those outlined in the MaterialX Developer Guideline section
1.6.2 Variable Naming Convention. <br>
<a href="https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md">https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md</a>
<o:p></o:p></li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ll make separate files for each of these models as well, and make all of them available for browser creators to test against if they are interested.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ll also take requests for other MaterialX test content as I have time to make it.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Aaron<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> X3D-Ecosystem <x3d-ecosystem-bounces@web3d.org>
<b>On Behalf Of </b>Bergstrom, Aaron via X3D-Ecosystem<br>
<b>Sent:</b> Thursday, February 26, 2026 8:44 PM<br>
<b>To:</b> X3D Ecosystem public discussion <x3d-ecosystem@web3d.org><br>
<b>Cc:</b> Bergstrom, Aaron <aaron.bergstrom@und.edu><br>
<b>Subject:</b> Re: [X3D-Ecosystem] Question for X3D Browser Developers<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Michalis,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for the in-depth explanation.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My naïve understanding of how shaders work have clouded my judgement. Still, our conversation and email yesterday has motivated to do something in this area.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I will focus my efforts on exporting the following tasks:<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l5 level1 lfo1">ND_surfacematerial as a PhysicalMaterial node with X_ITE Material Extensions. This is definitely easy enough.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l5 level1 lfo1">Export a PackagedShader version of ND_surfacematerial that uses MaterialX document if you, or anyone else, wishes to experiment with it.<o:p></o:p></li><ul style="margin-top:0in" type="circle">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l5 level2 lfo1">I’ll add the non build-in fields to the shader node at export.<o:p></o:p></li></ul>
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l5 level1 lfo1">And I’ll experiment with a ComposedShader version of it for X_ITE, and CGE if you like.<o:p></o:p></li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The MaterialX. GlslShaderGenerator does have some capability to change uniform names before generating the GLSL code. I’ll at least try to see how I can use that to get some kind of result for ComposedShader.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Aaron<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Michalis Kamburelis <<a href="mailto:michalis@castle-engine.io">michalis@castle-engine.io</a>>
<br>
<b>Sent:</b> Thursday, February 26, 2026 6:16 PM<br>
<b>To:</b> X3D Ecosystem public discussion <<a href="mailto:x3d-ecosystem@web3d.org">x3d-ecosystem@web3d.org</a>><br>
<b>Cc:</b> Bergstrom, Aaron <<a href="mailto:aaron.bergstrom@und.edu">aaron.bergstrom@und.edu</a>><br>
<b>Subject:</b> Re: [X3D-Ecosystem] Question for X3D Browser Developers<o:p></o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<ol start="1" type="1">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l3 level1 lfo2">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">To be clear, I second the idea to look at <a href="https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md#162-variable-naming-convention" target="_blank">https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md#162-variable-naming-convention</a> by
X3D browser implementors :) This proposes a standardized names for uniforms / attributes to pass to shaders for MaterialX. I am enthusiastic that our renderer (Castle Game Engine) could have an "alternative path" and generate uniforms / attributes this way,
and thus support MaterialX within X3D. See <a href="https://castle-engine.io/roadmap#material_x" target="_blank">https://castle-engine.io/roadmap#material_x</a> for my plans how I want to do this.<o:p></o:p></span></li></ol>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<ol start="2" type="1">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l4 level1 lfo3;list-style-type:"2. "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">However, I have to also point out some "bad news". It's <o:p></o:p></span></li><ol start="1" type="a">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l4 level2 lfo3">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">not as easy as using GLSL macros to normalize the names. I explain it below.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l4 level2 lfo3">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">and it's not a solution for everything. MaterialX only standardizes things it cares about for its use-case, see below; this is a not solution to solve X3D browser incompatibilities in what uniforms
/ attributes we accept, and I don't even think its possible to solve it -- browsers need special way to implement and optimize stuff on GPU, like shadows and skinned animation.<o:p></o:p></span></li></ol>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Details:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">IMO using #define , to "normalize" the GLSL incompatibilities between browsers using GLSL macros, is not going to work. It will definitely not work for Castle Game Engine --
the list you ask about is just impossible to provide from my side, as CGE author. I could only provide a very incomplete and thus useless version (since even i_position vs castle_Vertex has different type, see below).<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">The reason is that not only the names of uniforms all renderers (including all X3D browsers) use is different. Also our types, and expected usage, are different. Everyone is
passing data in different structures (and often for good reasons - we have different set of features, different subset of platforms we want to support, different optimizations we have). E.g.<o:p></o:p></span></p>
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<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">Light data, in "u_lightData" ( from <a href="https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md#162-variable-naming-convention" target="_blank">https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md#162-variable-naming-convention</a> )
is not something that any browser will have out of the box. We pass it in CGE without structures, using a combination of uniforms and #define conditionals, to make light computation as optimized as possible.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">Even simple things are incompatible. E.g. CGE has "castle_Vertex", which is almost like "i_position" that MaterialX defines... but our castle_Vertex are 4D (passed in homogeneous coordinates, for
good reasons -- we render also shadow quads for shadow volumes). While "i_position" is 3D. So even providing a simple rename for this most basic thing is impossible. Again, for good reasons. We can have "alternative MaterialX naming" in CGE, but you cannot
just rename "castle_Vertex -> i_position". We need our internal shaders to handle shadow quads for shadow volumes.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">CGE doesn't pass i_bitangent as an attribute, we pass only tangent (and we calculate bitangent in GLSL code).<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">CGE provides texture coordinates using various types - vec2, vec3, vec4, depending on the definition. (And for computed texture coords, in a different way.) So "i_texcoord_N" as "just vec2" as defined
by MaterialX is not possible. MaterialX doesn't account for non-2D and/or computed textures.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">Stuff like u_worldMatrix , u_worldInverseMatrix, u_viewMatrix etc. - we have this information, passed under certain conditions. For MaterialX, we would just pass it always, if shader linking stage
shows we have this uniform. But that's not something we do by default for internal shaders, as there's no need for it.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">The list goes on. For pretty much variable on the <a href="https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md#162-variable-naming-convention" target="_blank">https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md#162-variable-naming-convention</a> list: <o:p></o:p></span></li></ul>
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<span style="font-size:10.5pt;font-family:"Arial",sans-serif">A. it is _obvious how to implement support for it_ <o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">but also B. we _do not have a direct trivial equivalent for it right now_. Not something you can have just renaming castle_Xxx -> into standardized MaterialX name.<o:p></o:p></span></li></ul>
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<span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></li></ul>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">To be clear, I think the list of MaterialX is great, and I want to have CGE option to "generate uniforms / attributes following this convention". As we talked yesterday, as I
documented on <a href="https://castle-engine.io/roadmap#material_x" target="_blank">https://castle-engine.io/roadmap#material_x</a> . I would encourage other browser developers to look into this too -- to have an _option_ for this.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">But:<o:p></o:p></span></p>
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<span style="font-size:10.5pt;font-family:"Arial",sans-serif">You cannot achieve this by simple rename. The generation of MaterialX-compatible names requires cooperation from the rendering code (like Pascal code, in case of CGE; JavaScript code in case of X_ITE/X3DOM
etc.). You cannot just get it by renaming the uniforms/attributes generated now.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo5;list-style-type:"- "">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">Remember this is not a panacea for all shader incompatibilities:)<o:p></o:p></span></li></ul>
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<span style="font-size:10.5pt;font-family:"Arial",sans-serif">Material parameters (like uniform names for color, roughness etc.) are not standardized. Which is correct for the MaterialX use-case -- MaterialX consumes the material parameters, so when you export
it, you can set both the material parameter names (in ComposedShader, PackagedShader) and consume them (in shader code, in MarerialX XML or in GLSL).<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo5">
<span style="font-size:10.5pt;font-family:"Arial",sans-serif">There are still unsolved things. E.g. when using ComposedShader with GLSL generated -- we cannot have shadow map receiving, or skinned animation on GPU, since this requires both information (uniforms)
and shader code which our internal shaders have, but your generated ones will not.<o:p></o:p></span></li></ul>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Michalis<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">On Thursday, February 26th, 2026 at 16:59, Bergstrom, Aaron via X3D-Ecosystem <<a href="mailto:x3d-ecosystem@web3d.org">x3d-ecosystem@web3d.org</a>>
wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">X3D Browser Devs,<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">So all… please correct me if you think I’ve over simplified what I’ve written below.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Based on my conversation with Michalis, the existing X3D browsers (FreeWRL, X3DOM, X_ITE, and CGE) all have different
shader naming conventions for their GLSL uniform, in, and out variables.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Any particular browser’s naming convention may, or may not, match the list of MaterialX shader variable naming conventions
found at the url below:<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><a href="https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md" target="_blank">https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/documents/DeveloperGuide/ShaderGeneration.md</a><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">However, based on my reading, it seems to me that I can inject the proper naming conventions into the *.frag and *.vert
files as a ‘#define’ alias before writing the files to disk.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Then I could add your browser’s aliases to the field names of the exported X3D shader node.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">An injected alias would look something like this (just a random example of a GLSL shader alias):<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span class="hljs-meta"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> #define vd_tangentWorld vd.tangentWorld</span></span><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span class="hljs-meta"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> #define vd_normalWorld vd.normalWorld</span></span><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">I would ask that each browser vendor provide me with a list of the naming conventions for their browser shader’s naming
conventions that match up with the MaterialX naming conventions found at the link above.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">If I have that list, I can just add those alias’ to the GLSL file before writing it to disk, and write out a version
of the X3D shader that matches your browser’s naming conventions.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">I just need the alias list for your browser and we should be good to go for supporting MaterialX shader export from
Maya.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Aaron<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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