“BLEND” is a much nicer alphaMode value (if the hardware supports it – not a steep requirement) than “MASK” as mask is either fully opaque or fully transparent, depending on the alphaCutoff. This matches many other converters’ alphaMode default.
Before, models (of traditional lighting models) with specularity/glossiness would be completely flat when exported to metallicRoughness. These changes approximate glossiness (as an inverse of roughness, with specular intensity as a multiplier) both reading from gltf2 and writing to gltf2.
The changes here (which only apply to reading from or writing to pbrSpecularGlossiness) will:
- store and read specular color on `AI_MATKEY_COLOR_SPECULAR ` rather than `AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS_SPECULAR_FACTOR`
- store and read specular texture from `aiTextureType_SPECULAR` rather than `AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS_SPECULARGLOSSINESS_TEXTURE`. Even though pbrSG’s specularGlossiness texture uses the alpha channel for glossiness, it will still work well enough with just the RGB channels of the image
These changes do a better of importing and exporting baseColor colors and textures, as well as diffuse colors and textures (in the case of pbrSpecularGlossiness)
- baseColorFactor will be stored on both `$clr.diffuse` and `$mat.gltf.pbrMetallicRoughness.baseColorFactor`, and will be extracted from `$mat.gltf.pbrMetallicRoughness.baseColorFactor` first, and falling back to `$clr.diffuse`. The behaviour for baseColorTexture is similar
- pbrSG’s diffuseFactor will now only be store on `$clr.diffuse` (overwriting any previous assignments to `$clr.diffuse`, e.g. from metallicRoughness’ baseColorFactor, as diffuseFactor is more analogous to diffuse color than baseColor), and will only extract from `$clr.diffuse`
Text exporters are using string streams to hold the file content first and then write them to the file in a single pass. If for whatever reason the stream has the fail bit set, tellp() will return pos_type(-1), which in turn makes the subsequent write crash - at least on Windows systems. One reason for the stream being in fail state is when its size exceeds 2^31 bytes, even on 64-bit systems (i.e., when very large scenes get exported).
The fix is checking the fail() before even opening the file.
