Collision for Terrain Generated via Vertex Displacement / Informal Tutorial, Godot 4 Alpha 10 — Transcript

Full transcript

1. 0:00okay let's jump right into it I'm making
2. 0:02this video because I said I would make
3. 0:04it and a few people messaged me about it
4. 0:07so let's just get this over with and
5. 0:09move on to more uh fascinating things
6. 0:12how do you create a collision for a
7. 0:16Shader generated terrain Inca doll well
8. 0:19let me show you how to do it again as
9. 0:21with nearly everything else in Godot
10. 0:23there are multiple ways to bake a
11. 0:26collider for height mop terrain you can
12. 0:29also use the mesh tools and so on but
13. 0:31this one seems the easiest and indeed
14. 0:34the fastest and probably the intended
15. 0:36way to considering the name of the
16. 0:38resource that we're going to be using
17. 0:39Okay firstly in the Collision shape node
18. 0:43you have this property here called shape
19. 0:45which I'm sure you're well aware of what
20. 0:47you may have missed about it though is
21. 0:49that on the list of shapes here you have
22. 0:52this thing called height map shape 3D
23. 0:55and so if we go ahead and select it and
24. 0:58set the width and depth to let's say a
25. 1:01thousand by a thousand you'll see it
26. 1:04creates a collision mesh which is
27. 1:06nothing else but an array of height
28. 1:08values so if you click on this array
29. 1:10you'll see that we have all of our
30. 1:12height values here on this list there's
31. 1:15one for each vertex on this Collision
32. 1:17mesh that we've just created so if we
33. 1:20put a value in the first one let's say
34. 1:2350 you'll see that in the corner over
35. 1:25there there is a spike well that is
36. 1:28exactly the first vertex reaching the
37. 1:30height of 50. that's what's going on so
38. 1:33if I put a value into the second one and
39. 1:36the third one and so on you'll see how
40. 1:38it's starting to build a Terrain shape
41. 1:40now this means that if we can somehow
42. 1:43populate this map data array with height
43. 1:46map values from our height map image we
44. 1:49will be able to build the Collision
45. 1:51shape that will exactly match the
46. 1:53terrain shape which is what we're here
47. 1:55to do and we can do it with just a few
48. 1:57lines of code so let me show you this is
49. 2:01the script and before we go into it let
50. 2:03me just explain the setup real quick but
51. 2:06you can have a much simpler setup if you
52. 2:08want but I've decided to keep my
53. 2:10Collision nodes under this parent node
54. 2:13called terrain collisions because I'm
55. 2:16spawning and despawning collision chunks
56. 2:18as the player moves around the map and
57. 2:20the reason I have it set up like this is
58. 2:22well if you recall in from my previous
59. 2:24videos my terrain is infinite so I need
60. 2:27a way to dynamically create collisions
61. 2:30for the terrain chunk that I am
62. 2:32currently on and discard all the other
63. 2:34ones so my Collision script which
64. 2:37creates and manages Collision chunks is
65. 2:39attached to this parent node right here
66. 2:42so let's look at what we have in the
67. 2:43script if we want to generate a
68. 2:45collision shape from the height map we
69. 2:48must first deliver the height map into
70. 2:50it right so I'm getting mine from the
71. 2:53Shader param see my terrain node which I
72. 2:56creatively named Plane 2 has the vertex
73. 2:59Shader which stores the link to the
74. 3:01height map image so I'm just going to
75. 3:03grab it off of there it's just more
76. 3:05convenient for me to do it in this way
77. 3:07once we know where the height map image
78. 3:09is we can now go about creating the
79. 3:13Collision shape from it I built this
80. 3:16create Collision function for it and in
81. 3:19it we first set the scale of the
82. 3:22Collision node to match the scale of my
83. 3:25terrain Collision decimation is totally
84. 3:28optional it it's a means to generate
85. 3:31less detailed colliders basically for
86. 3:33example when your height map image is 4K
87. 3:37but it's not very rough you may want to
88. 3:41have a collision mesh that is 2K or even
89. 3:441K that should be good enough you may
90. 3:47not need all this detail in the
91. 3:48Collision mesh in which case you would
92. 3:50decimate the Collision mesh while
93. 3:53generating it I'll explain how it works
94. 3:55in just a moment okay next we need to
95. 3:58get the actual height map image uh for
96. 4:01this to work you need to make sure that
97. 4:03you import the height map image as an
98. 4:05image not as a texture we also need to
99. 4:08know what the height of the terrain is
100. 4:11this is the exact same value that you
101. 4:14used in your vertex Shader to create the
102. 4:17terrain displacement in the first place
103. 4:19I could just put the number here but
104. 4:22again I want to automate it so I'll just
105. 4:24grab the height of value from the
106. 4:27terrain Shader parameter and then this
107. 4:30is the decimation trick here okay I take
108. 4:33the height map image and resize it to
109. 4:35the height and width divided by the
110. 4:38decimation value so if the decimation
111. 4:40value is 2 which it is in my case we're
112. 4:44going to resize the image by half and
113. 4:46and that is going to produce a collision
114. 4:48shape that is uh you know half as
115. 4:52detailed as the terrain this is good
116. 4:55enough in my case the reason there's a A
117. 4:57plus one on the width and height is is
118. 5:01that if you don't add one more pixel
119. 5:02there will be a gap between two
120. 5:05neighboring Collision chunks the reason
121. 5:07for that is that in order to build one
122. 5:10quad of the Collision shape you need
123. 5:13four vertices so let's say your height
124. 5:15map image is three by three pixels so it
125. 5:17looks something like this you would
126. 5:19expect your Collision shape to also be
127. 5:22three by three right but in here if you
128. 5:25put map width and depth to three so
129. 5:27three by three you'll get this it's two
130. 5:30quads by two quads right it's one short
131. 5:32is this wrong no because vertex wise it
132. 5:36is three by three isn't it but since
133. 5:38this Collision shape is generated on the
134. 5:40basis of an image we want each pixel of
135. 5:43the image to build a quad otherwise we
136. 5:45can't really control the shape and
137. 5:47that's why you need to add this extra
138. 5:48row of pixels on each axis because that
139. 5:51will give you uh the extra row of
140. 5:53vertices and will patch this Gap okay
141. 5:55long story but hopefully it makes sense
142. 5:58next we need to create a a new height
143. 6:01map shape 3D resource and we're going to
144. 6:05assign it to the shape property of our
145. 6:07Collision shape node set the width and
146. 6:09depth using the resized image and then
147. 6:12what's left is to generate the float
148. 6:13array of height values to populate this
149. 6:17map data property and to do this we'll
150. 6:19Loop through the X and Y of the height
151. 6:22map image and get all the pixels of the
152. 6:26image and each pixels color Channel
153. 6:28we're going to multiply by the terrain
154. 6:31height value before pushing it into the
155. 6:33array I'm using the red channel here as
156. 6:35you can see the r but it doesn't really
157. 6:37matter which one you use it's a
158. 6:40grayscale image so all three channels RB
159. 6:43and G will have the same value anyway
160. 6:45and and that's it then we just feed the
161. 6:49float array into the map data parameter
162. 6:52on the shape property and we have our
163. 6:56Collision the rest of the script is
164. 6:57totally out of scope for this episode
165. 6:59but it's basically a Rough and Ready way
166. 7:01to move the Collision shape around the
167. 7:03world so that it's always under my feet
168. 7:06so just quickly the way I set this up is
169. 7:09I have this function here that creates
170. 7:11anchor points around the starting
171. 7:14position of the Collision node of the
172. 7:17first Collision node it has a radius
173. 7:19setting I have it hard set to 10 you can
174. 7:22set it to whatever you want meaning that
175. 7:24it will spawn Five 3D nodes in both
176. 7:27directions under x axis and then for
177. 7:31each Anchor Point it will create more
178. 7:33anchor points in each direction from
179. 7:36that Anchor Point on the y-axis so
180. 7:38effectively this function creates a grid
181. 7:41of anchor points around my starting
182. 7:44position and these anchor points are
183. 7:47used by the Collision chunk to attach
184. 7:49itself to so when I get close to an
185. 7:51anchor point the script will get a copy
186. 7:54of the active Collision chunk and attach
187. 7:57that copy to the Anchor Point that I'm
188. 7:59approaching and after I step onto this
189. 8:02new trunk and move away from the
190. 8:04previous chunk the previous chunk gets
191. 8:06discarded that's just how I did it you
192. 8:09can do it in your own way whatever works
193. 8:10for you well I hope this was helpful
194. 8:12stay tuned for the next episode in which
195. 8:15I'll explain how I got this infinite
196. 8:18grass thing going on using particle
197. 8:20shaders in God of four and it's going to
198. 8:22be a much nicer video leave a like if
199. 8:25you enjoyed this one consider
200. 8:27subscribing for more content if you want
201. 8:29more frequent updates follow me on
202. 8:31Twitter and now I guess I'll leave you
203. 8:33with a few of the recent Clips I
204. 8:37captured of my project when I was
205. 8:38testing the grass and other things
206. 8:39thanks for watching uh till next time
207. 8:42peace
208. 8:47foreign
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