Alpha coverage and optical transparency can be used at the same time so that some areas of a surface are transparent while others disappear entirely. Note that use of transmission values does not disallow usage of alpha coverage. The value is linear and is multiplied by the transmissionFactor to determine the total transmission value.
isn’t specularly reflected) is transmitted through. A value of 1.0 means that 100% of the light that penetrates the surface (i.e. transmissionTextureĪ greyscale texture that defines the amount of light that is transmitted by the surface rather than absorbed and re-emitted. A value of 1.0 means that 100% of the light that penetrates the surface is transmitted through. isn’t specularly reflected) rather than a percentage of the total light that hits a surface. This is a percentage of all the light that penetrates a surface (i.e. The amount of light that is transmitted by the surface rather than absorbed and re-emitted. Default is 1.33 which is IOR for liquid water. This will be multiplied by transmissionFactor.
The base percentage of light transmitted through the surface.Ī greyscale texture that defines the transmission percentage of the surface. These properties work together with the existing properties of the material to define the way light is modified as it passes through the substance. The third property defines the index of refraction of the material. Only three properties are introduced in this extension, two of which combine to describe a simple percentage of light that is transmitted through the material. The reference target of a rendering engine is assumed to follow the Painter's Algorithm. Note that, as rendering transparent objects presents many difficult-to-solve issues with primitive ordering, this extension does not dictate rendering algorithms. Alpha coverage and doubleSided properties still apply to transparent materials. When present, the extension indicates that a material should be rendered as a transparent surface and be blended as defined in the following spec. Extending MaterialsĪ transparent material is defined by adding the ADOBE_materials_thin_transparency extension to any glTF material. materials where only the surface is considered and not the volume) allows many simplifications to be made when calculating things like refraction and absorption. Dealing exclusively with “thin” materials (i.e. This extension aims to address the simplest and most common use cases for optical transparency: thin materials with no complex scattering (e.g. Note that alpha coverage can't make the surface colourless, nor can it leave the specular reflections unaffected. Alpha coverage of 20% (left) vs 100% optical transparency (right). Using alpha coverage of 0% would make the reflections invisible as well.
In the simplest case, specular reflections off the surface of the glass should still be visible on a fully transparent mesh. Transparent glass and plastics are great examples of this. However, most physical materials don’t fit into this category. Alpha coverage (exposed via the alpha channel of baseColorTexture) is useful for transparent materials such as gauze that don’t reflect, refract, absorb or scatter light. Many optically transparent materials are impossible to represent in a physically plausible manner with the core glTF 2.0 PBR material. Mike Bond, Adobe, Vendor Extension - Currently supported only in the web-publish feature of Adobe Dimension CC 2.0.ADOBE_materials_thin_transparency Contributors