I found a comment [1] on JBS stating that specular and self-Illumination alphas should be ignored, so it seems like there's at least 2 bugs here already.
https://bugs.openjdk.java.net/browse/JDK-8090548?focusedCommentId=13771150&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13771150 On Tue, Apr 26, 2022 at 4:25 AM Nir Lisker <nlis...@gmail.com> wrote: > Hi, > > Using the updated lighting test sample [1], I found some odd behavior with > regards to PhongMaterial: > > 1. The effect of the opacity (alpha channel) of a self-illumination map is > not documented, but lowering its value makes the object darker. I looked at > the pixel shader [2] and only the rgb components are sampled, so I'm a bit > confused here. What is the intended behavior? > > 2. The opacity of the object is controlled in the shader by both the > diffuse color and diffuse map. This is also not documented (although it > might be obvious for some). In the shader, the pixel (fragment) is > discarded only if the map is fully transparent (line 55), but not the > color. This leads to a situation where the object completely disappears > when the map is transparent, but not when the color is. In the shader, the > pixel should be transparent because of the multiplication of the alpha, but > it's not, so this is also confusing. Should they both have the same > contribution? Shouldn't it be valid to have a transparent diffuse but still > have specular reflections? > > 3. The specular map and color behave differently in regards to the > opacity. There is no documented behavior here. The alpha on the color is > ignored (it's used for the specular power), but not on the map - it > controls the reflection's strength, probably by making its color darker. In > the shader, lines 76-84 indeed ignore the alpha of the color, but take the > alpha of the map, although later in line 93 it's not used, so again I'm > confused. What's the intended behavior? > > 4. The specular map and color also behave differently in regards to the > reflection's strength. In the shader, this happens in line 78: the specular > power is corrected with NTSC_Gray if there is a map (with or without > color), but not if there's only a color. Shouldn't the contributions be the > same? Is the NTSC_Gray correction correct in this case? > > Thanks, > Nir > > [1] https://github.com/openjdk/jfx/pull/787 > [2] > https://github.com/openjdk/jfx/blob/master/modules/javafx.graphics/src/main/native-prism-d3d/hlsl/Mtl1PS.hlsl >
