Improve shader function descriptions (#9338)

- Move built-in shader function descriptions from Shading Language
  to a new page, with a format like the class reference.
- Shader built-in functions are sorted by category, each with a summary
  table and then full descriptions of each function, with parameters, 
  returns, and links to the official Khronos docs.

---------

Co-authored-by: clayjohn <[email protected]>
Co-authored-by: ashbygeek <[email protected]>
Co-authored-by: Yuri Rubinsky <[email protected]>
Co-authored-by: A Thousand Ships <[email protected]>
Co-authored-by: tetrapod <[email protected]>

_static/css/custom.css

@@ -810,6 +810,31 @@ html.writer-html5 .rst-content table.docutils th {
 .wy-table-responsive table.wrap-normal th {
     white-space: normal;
 }
+/* Turn nowrap on per-column */
+.wy-table-responsive table.nowrap-col1 td:nth-child(1),
+.wy-table-responsive table.nowrap-col1 th:nth-child(1) {
+    white-space: nowrap;
+}
+.wy-table-responsive table.nowrap-col2 td:nth-child(2),
+.wy-table-responsive table.nowrap-col2 th:nth-child(2) {
+    white-space: nowrap;
+}
+.wy-table-responsive table.nowrap-col3 td:nth-child(3),
+.wy-table-responsive table.nowrap-col3 th:nth-child(3) {
+    white-space: nowrap;
+}
+.wy-table-responsive table.nowrap-col4 td:nth-child(4),
+.wy-table-responsive table.nowrap-col4 th:nth-child(4) {
+    white-space: nowrap;
+}
+.wy-table-responsive table.nowrap-col5 td:nth-child(5),
+.wy-table-responsive table.nowrap-col5 th:nth-child(5) {
+    white-space: nowrap;
+}
+.wy-table-responsive table.nowrap-col6 td:nth-child(6),
+.wy-table-responsive table.nowrap-col6 th:nth-child(6) {
+    white-space: nowrap;
+}
 
 /* Make sure line blocks don't stretch tables */
 .wy-table-responsive table .line-block {
@@ -1136,6 +1161,7 @@ kbd.compound > .kbd,
 .classref-descriptions-group > p.classref-annotation,
 .classref-descriptions-group > p.classref-themeproperty,
 .classref-descriptions-group > p.classref-method,
+.classref-descriptions-group > div.classref-method.line-block,
 .classref-descriptions-group > p.classref-constructor,
 .classref-descriptions-group > p.classref-operator,
 .classref-descriptions-group > p.classref-constant,

tutorials/shaders/shader_reference/index.rst

@@ -10,6 +10,7 @@ Shading reference
    :name: toc-shading-reference
 
    shading_language
+   shader_functions
    shader_preprocessor
    spatial_shader
    canvas_item_shader