Changes between Initial Version and Version 1 of TechnicalArtRequirements

Timestamp:

May 24, 2023, 3:06:18 PM (12 months ago)

Author:

Stan

Comment:

Initial version by Vladislav

TechnicalArtRequirements

@@ +1 @@
+[[TOC]]
+= Technical Art Requirements =
+== Introduction ==
+Art content sets the style of the game and makes it beautiful, but at the same time it significantly
+affects performance and storage space. So we always have to balance between visual quality and
+technical limitations to make the game attractive and enjoyable.
+
+When you’re not sure does a guideline rule is applicable for you or not ask a question on the
+[https://wildfiregames.com/forum/ forums] or ask a programmer.
+== Textures ==
+=== Texture formats and sizes ===
+The game engine supports two common texture formats: [https://en.wikipedia.org/wiki/DirectDraw_Surface DDS] and [https://en.wikipedia.org/wiki/Portable_Network_Graphics PNG]. All new textures
+should be PNG by default, the engine will automatically convert them to [https://en.wikipedia.org/wiki/DirectDraw_Surface DDS].
+
+The engine supports only textures with a size of power of two: 4, 8, . . . , 1024, 2048. Maximum
+size is **2048**. It’s allowed to have different width and height, like 1024 × 4. Some platforms and drivers do not support non power of two textures, and it might cause unexpected crashes.
+
+A texture screen density should be accounted for the texture size choice. If an object covers a
+small part of a screen (like a flower), then the object doesn’t need a big texture.
+
+Do not use 64-bits textures, they will loose their precision anyway but will cost much more space
+in a repository.
+=== Ambient occlusion textures ===
+Ambient occlusion (AO) textures should not have noise. Noise increases sizes of [https://en.wikipedia.org/wiki/Portable_Network_Graphics PNG] files and adds artifacts to [https://en.wikipedia.org/wiki/DirectDraw_Surface DDS] files. If you don't see any noise in the game but only on a texture, then you are using a texture that's too big and you have to reduce its size and/or remove the noise.
+
+AO textures should not have alpha channel and saved as 8-bit grayscale [https://en.wikipedia.org/wiki/Portable_Network_Graphics PNG] files.
+
+{{{#!div style="font-size: 80%;text-align:center"
+{{{#!div 
+[[Image(ao-bad-good.png)]]
+}}}
+Figure 1: Ambient occlusion textures.
+}}}
+
+=== Normal map textures ===
+[NormalMaps Normal map] textures in the game engine are encoded using the classic method:
+
+(''Pixel,,Red,,'', ''Pixel,,Green,,'', ''Pixel,,Blue,,'') = (''Normal,,X,,'' ∗ 0.5 + 1, ''Normal,,Y,,'' ∗ 0.5 + 1, ''Normal,,Z,,'' ∗ 0.5 + 1)
+
+You have to avoid the following cases which might add noise and/or artifacts:
+* item normals lying on the surface, example Normal = (1, 0, 0), Pixel = (255, 127, 0)
+* item neighbour pixels with opposite directed normals, example:
+
+ ''Normal''1 = (1, 0, 0), ''Normal''2 = (−1, 0, 0),
+
+ ''Pixel''1 = (255, 127, 0), ''Pixel''2 = (0, 127, 0)
+
+=== Invisible faces ===
+You should avoid invisible faces, if a player can’t see a face in the game (during a usual gameplay
+or cinematic scene), then you have to remove it. For example you don’t need to have 5mm details
+on helmets.
+
+{{{#!div style="font-size: 80%;text-align:center"
+{{{#!div 
+[[Image(invisible-faces-bad.png)]]
+}}}
+Figure 2: Invisible faces for helmets.
+}}}
+
+=== Transparent meshes ===
+Avoid using transparent materials for meshes. If you can add some (5% - 10%) triangles but use
+opaque materials then use opaque materials. Make sure to still stay inside the recommended polycount.
+
+{{{#!div style="font-size: 80%;text-align:center"
+{{{#!div 
+[[Image(wireframe-bad-good.png)]]
+}}}
+Figure 3: Geometry for transparent meshes.
+}}}
+=== Bones ===
+For a good performance the number of bones should not exceed **32** bones for a single mesh. More bones means worse performance and bigger memory usage. The engine supports at most **64** bones per a mesh when gpu skinning is on.
+=== Bone Weights ===
+Every vertex in a rigged mesh should have be weighted to at least one bone. If they do not, they will cause glitches, and sometimes even a black screen.
+== Geometry ==
+=== Polycount Guidelines === 
+There is a good [ArtPolyCountGuidelines guideline] about poly count.
+=== Low poly tips ===
+There is a good generic [https://wildfiregames.com/forum/topic/18340-lowpoly-tips/ guideline] about low-poly geometry.
+
+=== Vertex and triangle count ===
+The game engine doesn’t support meshes with more than **65536** vertices. It means a mesh with
+3 unique vertices per triangle might have at most **21845** triangles. Reusing vertices might increase the maximum number of triangles.
+
+You should avoid spawning many small meshes, especially if they have less than 128-256 vertices.
+It’s better to pack them into a single mesh.
+
+== Materials ==
+
+=== Normal and specular textures ===
+Always use materials with both normal and specular textures. The engine will downgrade them for low-end hardware automatically using the shader quality option in the game.
+
+=== Parallax mapping === 
+Parallax mapping is allowed only on big and flat surfaces. [ParallaxNormalMaps Normals] of these surfaces (of all their vertices) should be co-directed (look in the same direction) and be perpendicular to the corresponding surface.
+
+{{{#!div style="font-size: 80%;text-align:center"
+{{{#!div 
+[[Image(parallax-bad-good.png)]]
+}}}
+Figure 4: Usages of parallax mapping.
+}}}
+
+=== External References === 
+* https://docs.unrealengine.com/4.27/en-US/TestingAndOptimization/PerformanceAndProfiling/Guidelines/
+* https://developer.arm.com/solutions/graphics-and-gaming/developer-guides/game-artist-guides
+* http://fragmentbuffer.com/gpu-performance-for-game-artists/
+* https://docs.cryengine.com/display/SDKDOC2/Rendering+Performance+Guidelines
+* https://blog.unity.com/technology/artists-best-practices-for-mobile-game-development