This presentation tackles the technical challenges behind the creation of Sleep Attack for iOS and Android, a 3D game with a 2D look, with all the movements of a 3D world. The challenges and solutions regarding the rendering process, the memory and the performance of the game were reviewed.

1. Sleep Attack TD
The Technical Post Mortem
Roberto Mangiafico

2. Gameplay Programmer in Ubisoft Milan since 2007
In 2012 left Ubisoft and created Bad Seed with other colleagues
About Me

3. Bad Seed

4. Sheep Up!

5. Sleep Attack

6. Sleep Attack: featuring and critics

7. Engine and Tools

8. 3D Camera in 2D game: Why
1. Circles in perspective
2. 3D movement feeling

9. 3D Camera in 2D game
Gameplay camera

10. 3D Camera in 2D game: Issue #1
Z fight problem
Not good looking perspective on objects

11. 3D Camera in 2D game: Issue #1
Solution: Every object is counter rotated towards the gameplay camera

12. 3D Camera in 2D game: Issue #1

13. 3D Camera in 2D game: Issue #2
Border artifact

14. 3D Camera in 2D game: Issue #2
Rendering order:
A
B
Draw B
 Blend border transparence with background color
 Write on the Z buffer
Draw A
 Find Z buffer with higher value
 Can’t blend with the B object border

15. Possible solution:
High value of cut off on the shader
Cons:
Very aliased borders
3D Camera in 2D game: Issue #2

16. Possible solutions:
Setup the camera to use Z distance only for rendering
order
Cons:
1. Very hard to manage for 200+ object per scene
2. Prompt to error
3. Don’t work for moving objects
3D Camera in 2D game: Issue #2

17.  Very high draw call number for mobile game
 200+ object per level
 Almost every object is animated
3D Camera in 2D game: Issue #3

18. Possible Solution:
Use Unity batching
Cons:
Objects must be static : No animation, No movement
3D Camera in 2D game: Issue #3

19. The Mesh Merger
 Create a big mesh with all the meshes vertices
 Apply the transforms animations of objects
 Keep the meshes UV’s
 Order the meshes from top to bottom of the screen
The solution we chose

20. Every mesh:
At scene loading register himself to its MeshMerger
Mesh Merger at mesh registration:
Store the vertices and the transform into a struct inside an array
containing all the registered meshes info
Mesh Merger – How it works

21. Mesh Merger at mesh registration:
 Disable the renderer of the registered mesh
 Order the vertices from up to bottom
Mesh Merger – How it works

22. Every frame:
 Apply the transformation to the vertices of the mesh
 Order the vertices from up to bottom IF NEEDED
Mesh Merger – How it works
…

23. Pro:
1. Resolve draw call issue
2. Resolve rendering order issues
3. Work with transform animated objects
4. Work with uv animated object
Cons:
1. Script a bit heavy on the cpu
2. All the meshes registered into a mesh merger must
have the same material
Mesh Merger

24.  No dynamic List<>
 Optimized for quad
Mesh Merger – Optimizations

25. Before:
Mesh Merger – Comparison
After:

26. Different screen ratio 16:9 – 4:3 – 1:1 – 3.2:19
Different resolutions and dpi
Problems:
• Adapt the HUD
• Adapt the 3D view
• Adapt the resolution for dpi
Different screen types

27. Adapt the HUD
Different screen types: Issue #1
New Unity GUI system not yet available
Created our own dynamic HUD system

28. Dynamic HUD system
• Dedicated camera
• 3D panels
• Position relative to screen

29. Adapt the 3D view
Different screen types: Issue #2
No need to change nothing for different ratio
Simply we see more background elements

30. Adapt for different resolutions
For devices with high resolution we needed an hd version
For almost everything we have a double version – SD and HD
HD has twice the resolution of SD
At the level load we load HD version if needed
Different screen types: Issue #3

31. Big memory load due to high number of textures with low
compression and sounds
Average 150MB for SD Level
Average 300MB for HD Level
1. Load only needed sounds and textures
2. Mid loading level
3. Load everything at startup, nothing during gameplay
4. Load only needed resolution HD/SD
Memory issues

32. Q/A

33. Thank you!