Docs: New Guide for adding art/sprites to Stonesense (#5207)

guide for adding art to Stonesense

Author: realSquidCoder

docs/changelog.txt

@@ -67,6 +67,7 @@ Template for new versions:
 - `spectate`: player-set configuration is now stored globally instead of per-fort
 
 ## Documentation
+- `stonesense-art-guide`: new guide for making sprite art for Stonesense
 
 ## API
 

docs/guides/index.rst

@@ -10,3 +10,4 @@ These pages are detailed guides covering DFHack tools.
    /docs/guides/modding-guide
    /docs/guides/quickfort-library-guide
    /docs/guides/quickfort-user-guide
+   /docs/guides/stonesense-art-guide

docs/guides/stonesense-art-guide.rst

@@ -0,0 +1,71 @@
+.. _stonesense-art-guide:
+
+Stonesense art creation guide
+=============================
+
+Understanding isometric perspective
+-----------------------------------
+
+Stonesense uses an isometric perspective, a form of pseudo-3D projection where objects are displayed at an
+angle, typically with a 2:1 pixel ratio for diagonal lines. This perspective allows for a detailed and visually
+appealing representation of a 3D world using 2D sprites. Unlike traditional top-down views, isometric projection
+simulates depth while maintaining a consistent scale without vanishing points.
+
+Understanding sprites
+---------------------
+
+Understanding how Stonesense deals with sprites is central to anyone who wishes to modify the content. The
+scheme is not very complicated, and this guide will give a short introduction to how they work. With the
+exception of floors, which we will discuss later, all sprites are 32x32 pixels and come in groups known
+as sprite sheets. All sprites are loaded and rendered in 32-bit full-color PNGs. The image files should have
+a transparent background but pure magenta (RGB: 255,0,255) is also treated as transparent.
+
+
+.. image:: ../images/stonesense-sprite-sample.png
+    :align: left
+
+Here's an example of a typical Stonesense sprite.
+
+When working with Stonesense sprites, it is important to understand how they fit into the isometric grid.
+Each sprite is designed to align with the isometric perspective and must fit within a specific bounding area.
+To illustrate this, here is a template for the area that should be used by Stonesense sprites:
+
+.. image:: ../images/stonesense-sprite-template.png
+    :align: left
+
+The solid area is the floor space taken up by a sprite, while the dotted box indicates the volume above this
+area corresponding to one z-level.
+
+The way sprites are loaded is fairly generalized: the name of the sprite sheet, and the index of a sprite within that sheet.
+
+Sprite sheets
+-------------
+There can be an arbitrary number of sprite sheets for Stonesense, though there are 3 sheets that are
+always present as they contain default sprites (see further down). Configuring the XML to use new sheets is
+outside the scope of this guide but there may be a guide for such added in the future.
+
+Sprite index
+------------
+The sprite index, or sheet index, is the zero-indexed offset of a sprite on its sprite sheet.
+The index starts with the upper left sprite which has index zero. It then increments to the right. Stonesense
+is hardcoded to 20 sprite-wide sheets, this means that anything past 20 "sprite slots" is ignored, though less
+than 20 slots is fine. The first sprite on the second row always has index 20 (even if there are fewer sprites per row in the sheet), the next row is 40, and so on. This
+boundary is hardcoded and changing the size of the sheet will not affect it.
+
+This image shows how sprites are indexed. Grid added for readability.
+
+.. figure:: ../images/stonesense-indexed-sprites.png
+    :align: left
+
+
+Important sprite sheets
+-----------------------
+`objects.png <https://github.com/DFHack/stonesense/blob/master/resources/objects.png>`_ is the default sheet
+for buildings and vegetation. Also used for all hard-coded content, like default plants, the cursor, default
+walls and liquid.
+
+`creatures.png <https://github.com/DFHack/stonesense/blob/master/resources/creatures.png>`_ is the default
+sprite sheet for creatures. If no file is specified in a creature node, this is the sheet it will use.
+
+`floors.png <https://github.com/DFHack/stonesense/blob/master/resources/floors.png>`_ holds all the Stonesense
+floors. Unlike the other sprite sheet, this sheet is hard-coded with sprite dimensions of 32x20 pixels.

docs/images/stonesense-indexed-sprites.png

@@ -78,10 +78,27 @@ line containing that folder, or :dffd:`use these smaller sprites <6096>`.
 Stonesense requires working graphics acceleration, and we recommend
 at least a dual core CPU to avoid slowing down your game of DF.
 
+Yellow cubes and missing sprites
+--------------------------------
+If you are seeing yellow cubes in Stonesense, then there is something on the map that
+Stonesense does not have a sprite for.
+
+.. figure:: ../images/stonesense-yellowcubes.png
+   :align: center
+
+   An example of the yellow cubes.
+
+If you would like to help us in fixing this, there are two things you can do:
+
+* Make an issue on `GitHub <https://github.com/DFHack/stonesense/issues>`_ with what
+  item is missing and pictures of what it looks like in DF.
+* Create the art yourself. For help with this, please see the `stonesense-art-guide`.
+
 Useful links
 ------------
 - Report issues on `Github <https://github.com/DFHack/stonesense/issues>`_
 - `support`
+- `Stonesense Subreddit <https://www.reddit.com/r/stonesense/>`_
 - :forums:`Official Stonesense thread <106497>`
 - :forums:`Screenshots thread <48172>`
 - :wiki:`Main wiki page <Utility:Stonesense>`