Merge pull request #1732 from RAMilewski/master

Update skin.scad

attachments.scad

@@ -409,7 +409,7 @@ _ANCHOR_TYPES = ["intersect","hull"];
 //   Things get difficult when the objects are curved, or even when their edges are not neatly aligned with the coordinate axes.
 //   In these cases, the library may provide multiple different anchoring schemes, called the anchor types.  When a module supports
 //   multiple anchor types, use the `atype=` parameter to select the anchor type you need.
-// .
+//   .
 //   First consider the case of a simple rectangle whose corners have been rounded.  Where should the anchors lie?
 //   The default anchor type puts them in the same location as the anchors of an unrounded rectangle, which means that for
 //   positive rounding radii, they are not even located on the perimeter of the object.

skin.scad

@@ -3526,10 +3526,6 @@ function associate_vertices(polygons, split, curpoly=0) =
     )
    associate_vertices(newpoly, split, curpoly+1);
 
-
-
-
-
 // Section: Texturing
 //   Some operations are able to add texture to the objects they create.  A texture can be any regularly repeated variation in the height of the surface.
 //   To define a texture you need to specify how the height should vary over a rectangular block that is repeated to tile the object.  Because textures
@@ -3611,12 +3607,15 @@ function associate_vertices(polygons, split, curpoly=0) =
 //   dots together.  But in 3D example we need to triangulate the points on a grid, and this triangulation is not unique.
 //   The `style` argument lets you specify how the points are triangulated using the styles supported by {{vnf_vertex_array()}}.
 //   In the example below we have expanded the 2D example into 3D:
+//   
 //   ```openscad
 //       [[0,0,0,0],
 //        [0,1,1,0],
 //        [0,1,1,0],
 //        [0,0,0,0]]
 //   ```
+//
+// Continues:
 //   and we show the 3D triangulations produced by the different styles:
 // Figure(3D,Big,NoAxes,VPR=[45.5,0,18.2],VPT=[2.3442,-6.25815,3.91529],VPD=35.5861):
 //   tex = [
@@ -3691,12 +3690,11 @@ function associate_vertices(polygons, split, curpoly=0) =
 //   extra points can be introduced in the interior of faces leading to unexpected irregularities in the textures, which appear
 //   as extra triangles.  These artifacts can be minimized by making the VNF texture's faces as large as possible rather than using
 //   a triangulated VNF, but depending on the specific VNF texture, it may be impossible to entirely eliminate them.
-// Figure(3D,Big,NoAxes,VPR=[140.9,0,345.7],VPT=[9.48289,-0.88709,5.7837],VPD=39.5401): The left shows a normal bricks_vnf texture.  The right shows a texture that was first passed through {{vnf_triangulate()}}.  Note the extra triangle artifacts visible at the ends on the brick faces.
+// Figure(3D,Med,NoAxes,VPR=[140.9,0,345.7],VPT=[9.48289,-0.88709,5.7837],VPD=39.5401): The left shows a normal bricks_vnf texture.  The right shows a texture that was first passed through {{vnf_triangulate()}}.  Note the extra triangle artifacts visible at the ends on the brick faces.
 //   tex = texture("bricks_vnf");
 //   cyl(d=10,h=15,texture=tex, tex_reps=[4,2],tex_samples=5,rounding=2);
 //   up(7)fwd(-3)right(15)cyl(d=10,h=15,texture=vnf_triangulate(tex), tex_reps=[4,2],tex_samples=5,rounding=2);
-
-
+//
 // Function: texture()
 // Topics: Textures, Knurling
 // Synopsis: Produce a standard texture. 
@@ -5262,8 +5260,42 @@ function _resample_point_array(data, size, col_wrap=false, row_wrap=false) =
       ]
   ];
 
-
-
-
+// Subsection: Textures from Graphic Images
+//   The BOSL2 scripts folder contains three scripts for creating texture arrays from graphic images.
+//   .
+//      - **img2scad.py** is a python script that creates a texture array from most common raster image formats, including gif, png, jpeg.
+//   .
+//      - **img2scad.html** contains a javascript creates a texture array from any image your browser can render.  
+//   .
+//      - **geotiff2scad.py** is a python script creates a texture array from geotiff depth maps.
+//   .
+//   Each of these scripts places a named array in an .scad file with names specified at run time.  Use include<> to add the array to your model. 
+//   .
+//   Both **img2scad.py** and **img2scad.html** provide similar capabilities, but the html script has a few additional capabilities
+//   as well as providing a graphical user interface.
+//   .
+//   On the right is a {{textured_tile()}} with the texture array created by **img2scad.html** from the .png file on the left:
+//   .
+//   ![Textured Tile](images/skin/WilburTex01.png)
+//   .
+//   The image luminance is directly translated into texture depth in the example above.  Better results can be obtained by passing 
+//   the original image through an AI image processor to produce a depth map from the image before creating the texture array.
+//   .
+//   ![Texture Tile](images/skin/WilburTex02.png)
+//   .
+//   AI image processing tool and workflows are still evolving rapidly. See the [discussion](https://github.com/BelfrySCAD/BOSL2/discussions/1731) on depth map workflows for current best practices.
+//   .
+//   Sources of whole planet GeoTIFF Data include:
+//      * [USGS Astrogeology Science Center](https://astrogeology.usgs.gov/search)
+//      * [NASA PDS (Planetary Data System)](https://pds.nasa.gov)
+//      * [OpenPlanetaryMap / OpenPlanetary](https://github.com/OpenPlanetary/opm)
+//   .
+//   GeoTIFF data for smaller areas comes from the Space Shuttle Radar Topography Mission. Data covering about 80% of the Earth's surface
+//   is available from [Earthdata](https://www.earthdata.nasa.gov/data/instruments/srtm/data-access-tools) 
+//   .
+//   A globe created using the **geotiff2scad.py** script to generate the texture array:
+//   .
+//   ![Geotiff Example](images/skin/globe_animation.gif)
+//   .
 
 // vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap