Infinite Terrain in Godot 4 - The 'Wandering' Clipmap Terrain Technique (with LOD) — Transcript

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1. 0:00all right ladies and gents i'm checking
2. 0:02in with another video good day to you in
3. 0:04today's episode of how to mess around in
4. 0:07godot 4 i'm going to take on a very
5. 0:09important subject
6. 0:11and that is terrain especially large
7. 0:14terrain or infinite terrain even
8. 0:16i have this interesting technique to
9. 0:18demonstrate today which i'm sure i
10. 0:20didn't invent i just don't know if it
11. 0:22has a name so for the purpose of this
12. 0:24video i'ma call it of the wandering
13. 0:26terrain uh technique now if you're a
14. 0:28godot developer you'll have heard of
15. 0:30zillan's height map terrain plug-in for
16. 0:32godot 3
17. 0:34and that is what i used to use
18. 0:36unfortunately zilen hasn't ported his
19. 0:38plugin to godot 4 yet and i haven't
20. 0:41found anything else that would be half
21. 0:42decent so i decided to play around by
22. 0:45myself
23. 0:46and there are at least a few good
24. 0:48approaches to creating cheap terrain in
25. 0:51godot
26. 0:52and they all have one thing in common
27. 0:54they use vertex shaders to deform a flat
28. 0:56mesh into a terrain well with this
29. 0:58technique you still need a mesh to begin
30. 1:00with right because the vertex shader as
31. 1:03you know doesn't create vertices it only
32. 1:05visually displaces existing vertices
33. 1:08so
34. 1:09my first idea was to create a grid mesh
35. 1:12in the blender and then chunk it up into
36. 1:14pieces bring it over to godot
37. 1:16and put a vertex shader on it that way
38. 1:19you could benefit from godot's frustum
39. 1:21culling to call out any chunks which are
40. 1:24outside of camera view this is the
41. 1:26approach wojtek used in his godot 4
42. 1:28forest demo which is freaking brilliant
43. 1:31if you haven't seen it go check it out
44. 1:33now the problem with trunks though is
45. 1:34that you can't use lod for the trunks
46. 1:36which are further out because when you
47. 1:38decimate a chunk mesh you'll see these
48. 1:41horrible looking cracks between the
49. 1:42chunks
50. 1:43so i thought
51. 1:45no i need a way to create various
52. 1:47resolutions on a single mesh i need to
53. 1:49be able to build a mesh from a height
54. 1:51map image and decimate the parts which
55. 1:53are further out but still it has to be
56. 1:55one mesh
57. 1:56so i started to experiment with
58. 1:58immediate mesh which used to be known as
59. 2:01immediate geometry in good o3 and i was
60. 2:03able to create vertices from pixels and
61. 2:06build triangles and quads from them and
62. 2:08it works but if i was going to collapse
63. 2:10the patches of vertices every other
64. 2:12frame or whatever i would need to
65. 2:14iterate through the arrays each time
66. 2:16which is simply not feasible in gd
67. 2:19script i mean you can do it in c plus
68. 2:21plus if you know how but i suck at c
69. 2:23plus plus so that was not an option for
70. 2:26me but the idea of having various
71. 2:28resolutions on a single mesh stuck with
72. 2:30me
73. 2:31i just i knew that this was the way i
74. 2:33just didn't know how to do it there are
75. 2:35two main approaches here one is called
76. 2:37quad tree and this one's about
77. 2:39subdividing a grid based on your
78. 2:40position
79. 2:42and and the other one
80. 2:44uses the so-called clip map which allows
81. 2:46you to decimate the patches of the mesh
82. 2:48that are further away from a certain
83. 2:49point more or less of course i mean
84. 2:51there's a lot more to it but the bottom
85. 2:53line is clip map was the one that i
86. 2:55wanted but i wanted it without gd native
87. 2:58and then it dawned on me that i could
88. 3:00just create a clip map mesh in blender
89. 3:03it into godot and rather than rebuild it
90. 3:05on every frame i could just project the
91. 3:07terrain onto it with a vertex shader and
92. 3:10then move the terrain with the player
93. 3:12and as i moved it i would offset the
94. 3:14terrain projection to reverse what the
95. 3:16movement has done to it meaning that if
96. 3:18i move the clip map plus one meter on
97. 3:20the x-axis for example
98. 3:22i would then move the projection by a
99. 3:24negative one meter on the x-axis to
100. 3:27counter the effect and that way the
101. 3:28projected terrain would be visually
102. 3:30locked in place while the clip map
103. 3:32itself would move around now the
104. 3:34benefits of this would be multiple but
105. 3:36most importantly it would be easy to set
106. 3:38up the clip map would only be drawn once
107. 3:41and the height map texture could be set
108. 3:43to repetitive meaning that the train
109. 3:45would be infinite without any impact
110. 3:47whatsoever on performance
111. 3:50so that's what i did and uh it works
112. 3:52pretty damn well i gotta say first i
113. 3:54built my clip mesh in blender it's easy
114. 3:57enough to do as you can imagine just
115. 3:58create a grid and subdivide it a few
116. 4:00times
117. 4:01then i built my vertex shader for it
118. 4:05it's a bit rough but you get the idea i
119. 4:07had to decompose the uv vector
120. 4:10in order to be able to export the uv x
121. 4:13and y as uniforms so that i could then
122. 4:15manipulate those variables in gd script
123. 4:18then i compose them back into the vector
124. 4:203 and connect into the texture 2d uv
125. 4:23slot and i also exported the height map
126. 4:25texture itself to a texture uniform so
127. 4:28that i could easily change it in the
128. 4:29inspector later and then i multiply the
129. 4:31y coordinate by height value which i
130. 4:33also exported to uniform
131. 4:35add the vertex input into it and connect
132. 4:37into the output boom done so in the
133. 4:40inspector you can see i have these
134. 4:42shader parameters now which i can
135. 4:44manipulate in code
136. 4:45and you can see if i scroll the uv
137. 4:47coordinates the projection moves as
138. 4:50expected if i set the height map
139. 4:52multiplier to something higher i get a
140. 4:53bigger amplitude and so on so next using
141. 4:56gd script i'm going to set the uvs to be
142. 4:58locked in place as the ground mesh moves
143. 5:01with the player
144. 5:02this is what the end result is going to
145. 5:04look like now hopefully you can see how
146. 5:06the terrain gets more detail as i
147. 5:07approach
148. 5:09all right let's uh jump into the script
149. 5:11i have this snap function which runs
150. 5:14once per second this is the function
151. 5:16that moves the clip mesh around the
152. 5:18world you don't really have to do it in
153. 5:19process because the clip map is set to
154. 5:22snap to grid so you're not gaining much
155. 5:24from running this function more
156. 5:26frequently except it would be eating
157. 5:28away on your fps you can see here the
158. 5:30player's global transform is using the
159. 5:32snapped function with a step variable
160. 5:35that is set to 20 meters so every time
161. 5:38the player moves 20 meters away from a
162. 5:40certain position the clip map will move
163. 5:42to that position and snap to grid uh the
164. 5:44reason snapping is important is that if
165. 5:46you unsnap it now actually let me move
166. 5:48the snap function to
167. 5:50process just for a second so you can see
168. 5:51the issue
169. 5:53if you unsnap it you'll get this
170. 5:55floating terrain effect which looks a
171. 5:57bit uh ridiculous so you do need to snap
172. 6:00it and it should always be snapped to a
173. 6:02round uh number the terrain is following
174. 6:04the player's x and y position right here
175. 6:07and i am offsetting the uv shader
176. 6:09parameters to keep the terrain
177. 6:11projection locked in place as the clip
178. 6:13map is following the player so basically
179. 6:16what i'm doing is reversing the effect
180. 6:18of the ground mesh movement by pushing
181. 6:21the uvs back by the same increment as
182. 6:23the movement increment and the way to
183. 6:25achieve this is to divide the uv value
184. 6:28by the size of your clip map mesh in
185. 6:30meters okay my clip map mesh is 000
186. 6:33meters so i divide the uvs by 2 000 and
187. 6:36i'm golden by the way if you want to use
188. 6:38a fragment shader to texture your
189. 6:39terrain which i'm sure you do
190. 6:41the rule is the same you have to do you
191. 6:44have to do the same thing for the
192. 6:46fragment shader otherwise the terrain
193. 6:48textures will move with you and that's
194. 6:50not what you want unless that's what you
195. 6:52want
196. 6:53performance seems pretty good if i
197. 6:55disable vsync i get about just under 500
198. 6:58frames per second without terrain
199. 7:00collision and some 380 to 400 frames
200. 7:04with collision i'm creating the
201. 7:05collision shape from the same height map
202. 7:07image which i'm using for the terrain
203. 7:10there is a simple although a little bit
204. 7:11tricky way to do this and i will explain
205. 7:14that in my next video where i'm also
206. 7:16expecting to be able to show you a way
207. 7:18to implement vegetation with this
208. 7:20technique
209. 7:21so stay tuned for that and in the
210. 7:23meantime do try out this technique and
211. 7:25let me know what results you get also
212. 7:27check my twitter for more frequent
213. 7:29updates i hope you enjoyed the video
214. 7:32i'll see you in the next one take care
215. 7:42[Music]
216. 7:51you