World/Udon Bugs & Feature Requests

Note: This request is an excerpt of this document which contains some additional context and suggestions for a implementation. With the introduction of VRCGraphics.Blit and asynchronous readback feature, we are closer than ever before to having compute-shader-like capabilities in VRChat. However, we are still missing a critical component: Random writes! Random writes are the ability to write to any location in a block of memory, represented as an unordered access view (UAV) - in our case, these UAVs concretely are just RenderTextures. Random writes are hugely useful for making compute-shader-like code performant, and for many of the things that people tend to use real compute shaders for, they are downright required. This is due in part to the fact that they enable the use of atomic operations (example), which open up the doors to a bunch of algorithms that are infeasible or very tricky to implement without. We could get very close to approximating compute shaders today with the addition of one single piece of API: Graphics.SetRandomWriteTarget . With this API, you can do random writes in fragment shaders, which brings them much closer to compute shaders (see the initial link for example code). Here are some examples of possible use cases: Persistent data storage in a shader without jank. No need for GrabPass abuse, Custom Render Textures, or Camera loops. Just bind a RenderTexture and you are good to go. Communication between shaders without jank. Simply bind your render texture, and any fragment shader can now access it with both read and write access. Custom realtime GI systems. I implemented a system that places and integrates light probes dynamically based on camera depth using this piece of API. Better fluid simulations. In general, pretty much any kind of shader-based simulation can benefit from this. Either by being made simpler to implement, faster, or becoming feasible in the first place. Potentially speedup for AudioLink's DFT algorithm? Fast reduce-style operations such as summing or maxing over a domain. GPU based sorting.

Similarly to picture loading, this feature would be great: Currently, systems in worlds with profiles (such as social worlds, leaderboards and such) rely on complex camera systems periodically capturing a single frame of the user's avatar in world, it is unoptimized, inaccurate, lag often leads to it being plain wrong or showing another user, etc With Udon access to profile pictures and an event on profile picture change, this would allow the users to have their chosen profile picture that vrchat already provides appear in those without the use of such systems, and would make such social profile/displays be a lot more interesting. Many worlds that focus heavily on social features and meeting people could heavily benefit from such feature.

VRC_Pickup.Drop exists, yet there is no way to force desktop users to automatically pick up an auto-hold enabled object. VR users currently wouldn't need this feature, as they can have pickups repeatedly moved to their tracking data hand position until they grip it. This feature would be useful for automatic inventory systems (desktop keyboard number keys or Half Life Alyx style VR menus)

Please add an event for when any player enters a station, including avatar stations. As of right now, OnPlayerTriggerExit is unreliable due to how Unity handles Trigger Exit events when colliders are disabled. Players entering a station will turn off their collider. While creators can handle this (although painfully) with stations in the world, it is impossible to handle it when the station is an avatar station. Related canny: https://vrchat.canny.io/sdk-bug-reports/p/playerlocal-collision-should-remain-on-players-in-stations

Summary The UdonSharp compiler compiles T[] declarations inside generic methods to an incorrect array type instead of the array type corresponding to the type argument. This issue occurs when T[] is used only within the method body and does not appear in the method's return type or parameters. Steps to Reproduce Create a UdonSharp script using the code below. Compile the script and inspect the generated Udon assembly, focusing on the code corresponding to each generic method invocation. Expected Result The array type should correspond to the specified type argument: GenericMethod<int>() : SystemInt32Array GenericMethod<float>() : SystemSingleArray GenericMethod<string>() : SystemStringArray Actual Result SystemInt32Array is used for all invocations. The corresponding array types for float[] and string[] are not generated. Reproduction Code using UdonSharp; public class GenericsArrayTypeBug : UdonSharpBehaviour { void Start() { GenericMethod<int>(); GenericMethod<float>(); GenericMethod<string>(); } public static void GenericMethod<T>() { T[] array = new T[0]; } } Generated Udon Assembly With SDK 3.10.5, the generated assembly uses SystemInt32Array for all three invocations, as shown in the following variable declarations: __lcl_array_SystemInt32Array_0: %SystemInt32Array, null __lcl_array_SystemInt32Array_1: %SystemInt32Array, null __lcl_array_SystemInt32Array_2: %SystemInt32Array, null The array constructor calls also use SystemInt32Array in all three cases: EXTERN, "SystemInt32Array.__ctor__SystemInt32__SystemInt32Array" Therefore, even when float or string is specified as the type argument, the array is compiled as the equivalent of int[] . Additional Observation When T[] is included in the method's return type or parameters, this issue does not occur, and the array type is generated correctly. Environment VRChat Worlds SDK: 3.10.5 Unity: 2022.3.22f1

As a world creator, you may have found yourself in need of a way to make an object always face the local player, sometimes called Billboarding. Doing this with transforms requires update loops in Udon, which are expensive. We’re adding native support for this to make it easier and more performant to implement! Three new methods will be available! (Note: always subject to change until release!) VRCBillboard.Register(Transform target); // upright, tracks yaw only (side-to-side) VRCBillboard.Register(Transform target, bool allowTilt); // allows up-and-down pitch changes as well VRCBillboard.Unregister(Transform target); // cleanup is automatic but can be triggered manually

ParticlePhysicsExtensions has various methods for getting particle collision data. Currently these methods are not exposed yet, so we cannot retrieve that data. Examples: https://docs.unity3d.com/ScriptReference/MonoBehaviour.OnParticleCollision.html

Allow world creators to access the user's status (blue green orange red) for in world actions Since there was recent talks about access to events related to friends invites and vrc+ status via udon, i thought this may be a really good addition that goes alongside this. For game worlds for example, users could be rewarded of being joinable by an xp boost, in social hubs have extra things / rooms if the user is in an open instance + green / blue, promoting accessible social statuses and sharing activities with others

This problem has become so rampant that it's causing infinitely more drama than the game has had in the past few months. Example: fried cortex and WALLNUTVEGASGUY

Please add Udon/UdonSharp API for controlling and reading the mouse cursor in Desktop Mode Currently, interacting with a custom world UI requires holding TAB to free the cursor. This is inconvenient for long interactions such as crafting, waiting for processes to finish, or using an inventory. Ideally, Udon should be able to: Release the mouse cursor from script. Read the cursor position (x, y) while it is being used by the world. For privacy, cursor position could automatically become unavailable whenever the user interacts with a VRChat-owned UI/menu. In that state, Udon would receive no cursor-position data. Once the user returns to the world, access could be restored. This would allow custom desktop UIs to work more like normal game interfaces without requiring the user to hold TAB for the entire duration of an interaction. Receiving the cursor position would also be useful for visualizing drag-and-drop interactions. For example, a world could display an item being dragged by the cursor, show where it will be placed, or provide visual feedback while moving UI elements.