Use luminance, not red, for compatibility with older shader.

dmurdoch · Feb 18, 2024 · 99df7cd · 99df7cd
1 parent 4f66c2e
commit 99df7cd
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/inst/htmlwidgets/lib/rglClass/shaders/rgl_fragment.glsl b/inst/htmlwidgets/lib/rglClass/shaders/rgl_fragment.glsl
@@ -203,12 +203,14 @@ void main(void) {
 #endif //TEXTURE_rgba
 
 #ifdef TEXTURE_alpha
+ float luminance = dot(vec3(1.,1.,1.),textureColor.rgb)/3.;
+
 #if defined(TEXMODE_replace) || defined(TEXMODE_decal)
- textureColor = vec4(lighteffect.rgb, textureColor.r);
+ textureColor = vec4(lighteffect.rgb, luminance);
 #endif 
 
 #if defined(TEXMODE_modulate) || defined(TEXMODE_blend) || defined(TEXMODE_add)
- textureColor = vec4(lighteffect.rgb, lighteffect.a*textureColor.r);
+ textureColor = vec4(lighteffect.rgb, lighteffect.a*luminance);
 #endif
 
 #endif // TEXTURE_alpha

diff --git a/man/material.Rd b/man/material.Rd
@@ -117,7 +117,8 @@ of objects in an \pkg{rgl} scene.
 in the display within R versus the WebGL display using
 \code{rglwidget()}. In particular, in WebGL 
 \code{textype = "alpha"} will always take the alpha value from
-the red channel of the texture, whereas the R display bases
+the luminance (i.e. the average of the R, G and B channels) 
+of the texture, whereas the R display bases
 the choice on the internal format of the texture file.
  }
  \item{texmode}{