This document discusses the creation of an IMGUI (Immediate Mode Graphical User Interface) called VUI. It begins with an introduction to the creator and their game FiKo which uses an IMGUI for its level editor. It then discusses Dear ImGui and Nuklear, two popular IMGUIs. The rest of the document focuses on explaining why IMGUIs are useful, how to build UI controls with them, different approaches to laying out controls, the data structure used for controls, and providing a high-level overview of the logic, rendering, and frame aspects of an IMGUI.

1. Writing an IMGUI
By Henry Rose
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2. Who Am I?
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Game Dev of a game called FiKo
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Creator of VUI (an IMGUI)
https://github.com/heroseh/vui
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Stream Mon – Fri 1PM GMT
https://twitch.tv/heroseh
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Twitter: @_herose_ 2

3. FiKo
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4. Level Editor with IMGUI
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5. VUI: an IMGUI
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6. What makes it different?
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User UI code runs every input event
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No control objects in user code
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Dynamic by default

7. https://youtu.be/Z1qyvQsjK5Y
Casey Muratori (2005)
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8. Dear Imgui (C++)
First - V1.0 released 11/08/14
Latest - V1.80 released 21/01/21 8

9. Nuklear (C)
First - V1.0 released 14/04/16
Is now maintained by the community
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10. Handmade Podcast Ep 3
https://handmade.network/podcast/ep/c1174949-adc4-492d-89b5-ca73dea4ff16
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11. Why IMGUI
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12. Why IMGUI - Retained
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13. Why IMGUI - Retained
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14. Why IMGUI - Retained
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15. Why IMGUI
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16. Why IMGUI
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17. How do you build controls?
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Button
Label
Grid
TextBox
CheckBox
RadioButton
ComboBox
Retained UI IMGUI
Control

18. How do you build controls?
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19. Build controls - stack
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[ ]

20. Problems of the stack approach
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Doing to much at once
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Fixed or Auto sizing only, cannot fill the
parent or ratio of parent
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Animation is harder since you create new
controls each time.

21. Build controls - tree
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Internal Build State Pointers
P = Parent Control
PS = Previous Sibling Control
P
P
PS
8
21
25
27
PS
PS

22. 22
Internal Build State Pointers
P = Parent Control
PS = Previous Sibling Control
P
P
PS
8
21
25
27
PS
PS
Build controls – tree (later iteration)
P
PS
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PS
17
PS
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23. Control data structure
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24. Control data structure
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25. Control data structure
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26. High Level Overview
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Logic
Rendering
Frame

27. 27
Logic
Rendering
Frame
High Level Overview

28. 28
Logic
Input – (User -> System)
Build UI - (User)
Layout - (System)
High Level Overview

29. High Level Overview - Logic
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30. 30
High Level Overview - Logic

31. 31
High Level Overview - Logic

32. 32
High Level Overview - Logic

33. 33
High Level Overview - Logic

34. How is one Designed? - Logic
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35. How is one Designed? - Logic
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36. 36
Logic
Rendering
Frame
High Level Overview

37. High Level Overview
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Logic
Rendering
Frame

38. Thank you for watching
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39. Questions?
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