3D scatter plot not drawn by z-axis order when alpha != 1

[schuemie]

When creating a 3D scatter plot, the dots should be drawn in the order of depth, so drawing the furthest dot first, to get the right occlusion. This works well when alpha = 1, but when alpha < 1 the dots seem to be drawn in order of categories instead.

Here's a simple example. If you rotate it so the green dot is at the forefront, it is nevertheless occluded by the blue dot:

library(plotly)
plot_ly(data = data.frame(x = c(1, 1),
                          y = c(1, 2), 
                          z = c(1, 1), 
                          class = c("A", "B")),
        x = ~x, 
        y = ~y, 
        z = ~z, 
        color = ~class,
        alpha = 0.9)

This especially problematic when you have a lot of dots, and a cluster of nearby dots is completely hidden by a faraway cluster of dots of a different color.

> sessionInfo()
R version 4.0.3 (2020-10-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18363)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                           LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] plotly_4.10.0 ggplot2_3.3.5

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.7         pillar_1.6.4       compiler_4.0.3     later_1.3.0        RColorBrewer_1.1-2 tools_4.0.3        digest_0.6.28     
 [8] viridisLite_0.4.0  jsonlite_1.7.2     lifecycle_1.0.1    tibble_3.1.5       gtable_0.3.0       pkgconfig_2.0.3    rlang_0.4.11      
[15] shiny_1.7.1        DBI_1.1.1          crosstalk_1.1.1    yaml_2.2.1         fastmap_1.1.0      httr_1.4.2         withr_2.4.2       
[22] dplyr_1.0.7        htmlwidgets_1.5.4  generics_0.1.0     vctrs_0.3.8        grid_4.0.3         tidyselect_1.1.1   data.table_1.14.2 
[29] glue_1.4.2         R6_2.5.1           fansi_0.5.0        farver_2.1.0       tidyr_1.1.4        purrr_0.3.4        magrittr_2.0.1    
[36] scales_1.1.1       promises_1.2.0.1   ellipsis_0.3.2     htmltools_0.5.2    assertthat_0.2.1   mime_0.12          colorspace_2.0-2  
[43] xtable_1.8-4       httpuv_1.6.3       utf8_1.2.2         lazyeval_0.2.2     munsell_0.5.0      crayon_1.4.1   

[brooksambrose]

Pro tip, search if the issue exists before wasting time on a reprex 😂. I would add that this is an especially prevalent bug since the default is to render 3D bubbles and apply transparency when using the size argument.

library(plotly)
d<-rbind(
  data.frame(x=3,y=3,z=3,g='A')
  ,data.frame(x=2,y=2,z=2,g='B')
  ,data.frame(x=1,y=1,z=1,g='C')
)

p<-plot_ly(d,x=~x,y=~y,z=~z,color=~g,size=~I(pi*1000*(3:1)^2))
# Fine
p %>% add_markers(marker=list(opacity=1))

# Far points render in front of near points
p %>% add_markers(marker=list(opacity=.99))

^{Created on 2022-01-31 by the reprex package (v2.0.1)}

Session info

``` r sessioninfo::session_info() #> ─ Session info ─────────────────────────────────────────────────────────────── #> setting value #> version R version 4.1.2 (2021-11-01) #> os macOS Monterey 12.1 #> system aarch64, darwin20.6.0 #> ui unknown #> language (EN) #> collate en_US.UTF-8 #> ctype en_US.UTF-8 #> tz America/Los_Angeles #> date 2022-01-31 #> pandoc 2.14.0.3 @ /Applications/RStudio.app/Contents/MacOS/pandoc/ (via rmarkdown) #> #> ─ Packages ─────────────────────────────────────────────────────────────────── #> package * version date (UTC) lib source #> backports 1.2.1 2020-12-09 [1] CRAN (R 4.1.1) #> callr 3.7.0 2021-04-20 [1] CRAN (R 4.1.1) #> cli 3.1.0 2021-10-27 [1] CRAN (R 4.1.1) #> colorspace 2.0-2 2021-06-24 [1] CRAN (R 4.1.1) #> crayon 1.4.2 2021-10-29 [1] CRAN (R 4.1.1) #> crosstalk 1.1.1 2021-01-12 [1] CRAN (R 4.1.1) #> curl 4.3.2 2021-06-23 [1] CRAN (R 4.1.1) #> data.table 1.14.3 2021-10-04 [1] local #> digest 0.6.29 2021-12-01 [1] CRAN (R 4.1.2) #> dplyr 1.0.7 2021-06-18 [1] CRAN (R 4.1.1) #> ellipsis 0.3.2 2021-04-29 [1] CRAN (R 4.1.1) #> evaluate 0.14 2019-05-28 [1] CRAN (R 4.1.1) #> fansi 1.0.0 2022-01-10 [1] CRAN (R 4.1.2) #> farver 2.1.0 2021-02-28 [1] CRAN (R 4.1.1) #> fastmap 1.1.0 2021-01-25 [1] CRAN (R 4.1.1) #> fs 1.5.2 2021-12-08 [1] CRAN (R 4.1.2) #> generics 0.1.1 2021-10-25 [1] CRAN (R 4.1.1) #> ggplot2 * 3.3.5 2021-06-25 [1] CRAN (R 4.1.1) #> glue 1.6.0 2021-12-17 [1] CRAN (R 4.1.2) #> gtable 0.3.0 2019-03-25 [1] CRAN (R 4.1.1) #> highr 0.9 2021-04-16 [1] CRAN (R 4.1.1) #> htmltools 0.5.2 2021-08-25 [1] CRAN (R 4.1.1) #> htmlwidgets 1.5.4 2021-09-08 [1] CRAN (R 4.1.1) #> httr 1.4.2 2020-07-20 [1] CRAN (R 4.1.1) #> jsonlite 1.7.2 2020-12-09 [1] CRAN (R 4.1.1) #> knitr 1.37 2021-12-16 [1] CRAN (R 4.1.2) #> lazyeval 0.2.2 2019-03-15 [1] CRAN (R 4.1.1) #> lifecycle 1.0.1 2021-09-24 [1] CRAN (R 4.1.1) #> magrittr 2.0.2 2022-01-26 [1] CRAN (R 4.1.2) #> mime 0.12 2021-09-28 [1] CRAN (R 4.1.1) #> munsell 0.5.0 2018-06-12 [1] CRAN (R 4.1.1) #> pillar 1.6.4 2021-10-18 [1] CRAN (R 4.1.1) #> pkgconfig 2.0.3 2019-09-22 [1] CRAN (R 4.1.1) #> plotly * 4.10.0 2021-10-09 [1] CRAN (R 4.1.2) #> processx 3.5.2 2021-04-30 [1] CRAN (R 4.1.1) #> ps 1.6.0 2021-02-28 [1] CRAN (R 4.1.1) #> purrr 0.3.4 2020-04-17 [1] CRAN (R 4.1.1) #> R.cache 0.15.0 2021-04-30 [1] CRAN (R 4.1.1) #> R.methodsS3 1.8.1 2020-08-26 [1] CRAN (R 4.1.1) #> R.oo 1.24.0 2020-08-26 [1] CRAN (R 4.1.1) #> R.utils 2.11.0 2021-09-26 [1] CRAN (R 4.1.1) #> R6 2.5.1 2021-08-19 [1] CRAN (R 4.1.1) #> RColorBrewer 1.1-2 2014-12-07 [1] CRAN (R 4.1.1) #> reprex 2.0.1 2021-08-05 [1] CRAN (R 4.1.2) #> rlang 0.4.12 2021-10-18 [1] CRAN (R 4.1.1) #> rmarkdown 2.11 2021-09-14 [1] CRAN (R 4.1.1) #> rstudioapi 0.13 2020-11-12 [1] CRAN (R 4.1.1) #> scales 1.1.1 2020-05-11 [1] CRAN (R 4.1.1) #> sessioninfo 1.2.2 2021-12-06 [1] CRAN (R 4.1.2) #> stringi 1.7.6 2021-11-29 [1] CRAN (R 4.1.2) #> stringr 1.4.0 2019-02-10 [1] CRAN (R 4.1.1) #> styler 1.6.2 2021-09-23 [1] CRAN (R 4.1.1) #> tibble 3.1.6 2021-11-07 [1] CRAN (R 4.1.2) #> tidyr 1.1.4 2021-09-27 [1] CRAN (R 4.1.1) #> tidyselect 1.1.1 2021-04-30 [1] CRAN (R 4.1.1) #> utf8 1.2.2 2021-07-24 [1] CRAN (R 4.1.1) #> vctrs 0.3.8 2021-04-29 [1] CRAN (R 4.1.1) #> viridisLite 0.4.0 2021-04-13 [1] CRAN (R 4.1.1) #> webshot 0.5.2 2019-11-22 [1] CRAN (R 4.1.1) #> withr 2.4.3 2021-11-30 [1] CRAN (R 4.1.2) #> xfun 0.29 2021-12-14 [1] CRAN (R 4.1.2) #> xml2 1.3.3 2021-11-30 [1] CRAN (R 4.1.2) #> yaml 2.2.1 2020-02-01 [1] CRAN (R 4.1.1) #> #> [1] /opt/homebrew/lib/R/4.1/site-library #> [2] /opt/homebrew/Cellar/r/4.1.2/lib/R/library #> #> ────────────────────────────────────────────────────────────────────────────── ```

[twitwi]

cross referencing an issue on the js repo https://github.com/plotly/plotly.js/issues/1267