Raycasts, Explained. Every Physics "Cast" Visualized | Unity Tutorial
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- Äas pĆidĂĄn 26. 06. 2024
- Many of us kind of jumped into gamedev without a solid understanding of these Physics APIs such as Raycast and Spherecast. In this video I aim to make it really clear how each of the Ray, Sphere, Box, and Capsule casts work, look, behave, and how you can use each one of them to achieve your "casting" goals!
In this tutorial video you can see the following "casts" visualized:
1. Raycast
2. RaycastAll
3. Spherecast
4. SpherecastAll
5. Boxcast
6. BoxcastAll
7. Capsulecast
8. CapsulecastAll
each with different variations with trigger collision, layer masking, and more!
With 19 customizable scenarios, you know the full project being available on GitHub (github.com/llamacademy/raycas...) will help you better understand how to use each of these fundamental gamedev functions!
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Most tutorials come from knowledge gained making survival.llama.software Llama Survival - a top-down zombie survival shooter for Android and iOS.
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Chapters:
00:00 What are Raycasts?
03:19 Raycasts Visualized
05:00 Raycast All Visualized
06:48 Ultimate Fantasy Unity RPG Developer Bundle!
08:23 Spherecast Visualized
09:02 Boxcast Visualized
09:53 Capsulecast Visualized
11:15 SpherecastAll Visualized
12:37 BoxcastAll Visualized
13:08 CapsulecastAll Visualized
14:19 The NonAlloc-Variants
This video deserves more views. I feel like there is no reason to watch any other raycast video!
I'm very appreciative for you taking the time to document this so thoroughly!
Just found your video, been fighting a Dash move where I was seeing players dashing through fences and through small gaps sometimes due to a bad raycast setup. Switched to a BoxCast and its all working now, never knew that existed, super useful video!
Specially love the last part.
Know your tools helps you build better and faster. Thanks
Beautiful explanation and demo! Keep up the great work!
Thank you đ!
wow, that was very educative and helpful. Great explanation keep it going!
thanks so much, really appreciated the depth as well as the time you took to learn and demonstrate in scene. keep up the great academy work!
Great stuff as always! Thank you for the video!
That was a very good explanation, keep up the good work!
Thank you for this excellent resource and your encouragement/positivity!
You are so welcome! đ
Wow this was a really high quality explanation!
this is the best unity's raycast visualization on youtube !
much appreciated for the visualization !
You're very welcome đ
This is exactly what I was wondering, thank you so much
Glad it was helpful!
thank you, you helped me understand the nonalloc variants and how to use it
WOW nice effort to show all this Thanks
Best raycast tutorial in YT.
So cool! thank you very much
how can you have some dislike ?? you did a great job and you give the project !! damn +1
Wow this is great đđŒ
love your intro. that never gets old for me.
âș thanks. It's one of my favorite parts
Damn, I finally understand spherecast, I was thinking like it only casts sphere to end point but seeing it animated fixed it for me. It has no difference than Raycast, it was my mistake to think otherwise!
Thank you you so much, the visuals are awesome!!! I'm curious if you have a video on the frame generations of this?Are these generated every frame or in relation to rendering in some form
Like to see more unity physics and job system videos đ
really helpful thank you
You're welcome! đ
This is pretty helpful information for me (yeeesss me). Jokes aside I never knew about the QueryTriggerInteraction enum. Neat!
đ
Plz do more videos about using raycast and job system and rigidbody calculations with job system â€ïžâ€ïžâ€ïžâ€ïž
How did you make those casts slower than usual?
Did you code them again by checking collisions?
đ the cast itself still only happens in 1 frame. I have just shown a visualization slowly to make it more understandable. You can see exactly how I did it if you check out the project on GitHub: github.com/llamacademy/raycasting-explained
Great video! Do you think a boxcast might be a good way to deal with super fast sword slices instead of relying on Unity's collision detection? I'm thinking I might boxcast a weapon's box collider a set distance forward for every Update cycle while the weapon is in an "attack is active" mode. If it hits a player or something "hittable" then we simulate a collision. I've been messing with the different collision detection modes Unity offers on the rigid body but none have really gotten me quite where I want ...
It could work, but most likely your slash doesn't move perfectly linearly (but instead, more likely spherically) which can result in misses when your visual representation would have hit. For a sword slash I think you want "Continuous Dynamic" on a Rigidbody that is moving to get the proper collision.
@LlamAcademy thanks for the reply! I've tried dynamic and speculative and both work 9 out of 10 times ... but I want 10/10. I'm thinking I fire a rectangle shaped ray the width and length of the blade each frame and see what kind of precision is possible. I don't want to have to slow down the attack speed it seems less realistic đ . Love your vids btw.
Hope to adapt this in godot after the recent developments:(
Thanks for the amazing tutorial!!!
If I do switch to GodotâŠ. I have a big backlog of videos to port over đ this will definitely be one of them!
Hi, super informative tutorial!
If I want to check if 2 specific objects have been hit by RaycastAll, and I only want to do something if both objects have been hit, not just one, what would be the best way to track that?
Sorry it's more of a programming question instead of a raycast question, but figured I'd ask on the off-chance of some suggestions/recommendations
I think the most simple way would be to iterate over all the colliders hit by the RaycastAll/NonAlloc and check if both have been hit with a boolean like bool hitObject1, hitObject2; then assign them to true if the Raycast hit collider is the target object
@@LlamAcademy Thank you so much! :)
Danke!
Wow! Thank you! 𧥠I appreciate that!
awesome explanation man this is awesome! and i wanted to ask if you could make a tutorial for wall penetration or enemy body penetration. if you have time. thank you.
I have that on my list of topics! I plan on covering that as part of a gun & bullet series
@@LlamAcademy Ok cool good to know and thanks for responding.
Trying to use the ray cast to allign a sphere to the surface of the ground and get the angle of the normal like sonic the hedgehog. Help please
The RaycastHit has a "normal" property. Is that what you are looking for? docs.unity3d.com/ScriptReference/RaycastHit.html
@@LlamAcademy how can I keep the player above the surface of the ground? Or colliding with the ground. Keeping it aligned with the surface
you, yes you!
đâ€
cool video
Theres also navmesh cast. Its kinda used when you want to know if agent see a spot
True! I was only thinking of physics casts, but the NavMesh cast is very similarly useful for checking if a NavMeshAgent will hit something when traversing on the NavMesh
Man, you really are a teaching god. You give every explanation and every possible scenario. I really hope you can continue to help us achieve our dreams. I'll particularly try to help you on patreon as quickly as I can, even if it's on the simplest levels. And when I have a better condition, I will be at the highest levels to be able to help you as much as possible.
Wow! I really appreciate that! You are awesome đ€
I agree this is really amazing. Thank you so much!
I'm working on a custom raycast implementation for a programming challenge and I am wondering whether, after creating a ray using ViewportPointToRay, would it be possible to check whether this ray has intersected with a mesh rather than with a collider?
I think that is feasible. It likely will be slow because youâll have to check the bounds / triangle positions of each possible mesh and compare it outside the physics system. Youâll basically be rewriting a portion of the physics system
@@LlamAcademy In my situation there is fortunately only one object, unfortunately it is a sphere and that could make this a lot more complex đ
Hi! Can I ask Something? Is the Spherecast drawing a sphere with multiple raycasts all around?
Of course you can ask đ. That is not how the spherecast works though. Remember that a Ray is an incredibly thin line, so to construct a sphere with these would be extremely computationally expensive because we'd have to do thousands or millions of raycasts to ensure nothing was missed!
You can think about it as if you were to actually take a sphere and move it along the path you are "casting" on and that will (hopefully!) eventually hit something
@@LlamAcademy Thanks for the answer đ
arrow forward once to get "Analog app 1 TE" like he uses in the video or simply find one you'd like to use alternatively instead.
I am a little confused on the sphere cast, im not sure how you get an output from it, Im really new to development and I am checking if something is above my head while i crouch, I had it working with a raycast but the cast was to thin to can the roof above the corner of my head, this would cause me to jump while coming out of a tunnel i was crouched in, the raycast just returned true or false, I tried using sphere cast in the exact same context but it wouldnt work, does anyone have the solution to this, am i just being stupid?
You should be able to replace the Raycast exactly with a Spherecast but you have to remember to give the spherecast a radius as well. Everything else between them works the exact same way!
damn its work
Please please make a video explaining raycasting on Canvas UI elements (floating world UI). I can't for the life of me get a hit on a canvas raw image, unless I put a 3D Box Collider on it, which seems so wrong and I don't want to do.
That is a great idea for a topic! Thank you đ
@@LlamAcademy I'm always impressed and appreciative when a youtuber replies to their viewers, and also so quickly :)
Looking forward to this quick video!
@@ThanksForAllMyToes I try to respond to all of the questions! For an education channel I think it doesn't make a lot of sense to post content and not respond when someone has a question đ
what is a sphere cast's step? I find it inconsistent depending on circumstances...
What do you mean by âstepâ?
well, from what I am understanding is that spherecast works under the hood the following way: a sphere test is being performed every X distance for the total distance specified in the specified direction. If that's correct, then what is the step distance between each sphere test?
I donât think thatâs correct. Each of these casts occurs in a single frame based on the current physics world. The sphere/box/capsule/ray moves continuously until it makes contact or runs out of distance. What youâre describing sounds more like if you were checking with some script via FixedUpdate, the âstepâ would be however far you move the object in between calls to fixed updated based on the physics update interval. For most things on Physics that have a step, Unity provides a configuration option for it here: docs.unity3d.com/ScriptReference/Physics.html
so what is the implementation behind a sphere cast? is it some kind of a mathematical formula that checks for interception? or is it doing many sphere tests along the line for a distance specified?
I donât know how Unity has implemented it. The only information they give is here: docs.unity3d.com/ScriptReference/Physics.SphereCast.html which does not mention implementation details.
And really, the results are what weâre interested in. If we care deeply about how itâs implemented, thatâs when we start going down the custom engine rabbit hole.
Poor Ray, he gets so abused... casting and all...
markiplier
where that GraphicRaycaster.Raycast at???? HMMMM ???
oof. Got me on that one đ