unity shit

This is v. similar to the previous flocking post, only now we use a skinned & animated mesh & it's attached Animator component. Something to note, one instance of the prefab has to be in the scene, or it doesn't work (move it off camera or something). Also - the material that uses the surface shader , must have the GPU instancing enabled! That's what those if-checks are for! The gist of this is - we need to store the vertex animation into another buffer. The compute shader doesn't deal with this data at all - it is only concerned with the position/direction of each instance. It is the surface/vert-frag shader that will deal with it. The only bit the compute shader does increment is the "frame" of animation, which is determined by the speed at which the boid is moving.    C# SCRIPT using System.Collections; using System.Collections.Generic; using UnityEngine; public class SkinnedFlocking : MonoBehaviour {     public struct Boid     {  ...

Instead of getting data back from the GPU buffer, we're gonna use this code- Graphics.DrawMeshInstancedIndirect(boidMesh, 0, boidMaterial, bounds, argsBuffer, 0); - to draw instances of a mesh. Note the argsBuffer - this is a new type of buffer, containing arguments. It is defined  in the C# script and we're only initialising the first 2 entries of the array that we fill the argsBuffer with. It can actually hold a lot more information, but for this example, we only provide it with the index of the mesh and the number of them we want to draw. Argument Buffers seem to be very specific to this type of instanced mesh drawing in Unity. It doesn't seem easy to find information about them...  The compute shader and frag/vert shader are not directly concerned with the argument buffer, it seems that the code above is the only actual reference to the argsBuffer! The compute shader only updates the position/direction of the boids. The frag/vert shader (which is actually a surface shad...

This is more or less the same as the last wall of code. However this time, we are using the Graphics draw to draw a quad, which consists of Four points, Two triangles. We need to adjust our buffer and create a new struct for this, as well as initialise our arrays in a specific way to ensure the quads are facing the correct direction.   As mentioned, our new Struct - Vertex stores a position, UV value and life. We're going to use the Compute Shader to calculate the postion of each particle-  but then draw a quad at that position. We set the specific values for the vertices in the compute shader too. (the UVs don't change for each quad, so we set that value in the C# script)     //Triangle 1 - bot left, top left, top right     vertexBuffer[index].position.x = p.position.x - halfSize;     vertexBuffer[index].position.y = p.position.y - halfSize;     vertexBuffer[index].position.z = p.position.z;     vertex...

A post for reference really... Not a lot of magic here - except we're using a Graphic procedural - a point- to draw particles. To do this we calculate the position of the particles in the compute shader, then a standard vert-frag shader assigned to a material reads from the gpu buffer and draws the points accordingly. We're also getting the mouse position on screen converted to World Space & having the particles follow that coordinate.  The C# is as follows, careful with the comments i've left...blogger's formatting is a bit wonky - using System.Collections; using System.Collections.Generic; using UnityEngine; #pragma warning disable 0649 public class particle_dave : MonoBehaviour {     private Vector2 cursorPos;     // struct of a particle, fairly simple attributes     struct Particle     {         public Vector3 position;         public Vector3 vel...

 Use case - get the GPU to calculate a bunch of X,Y,Z coordinates for an arbitrary number of instanced prefabs in Unity.  On the Unity C# side, we need : To specify a compute shader, a handle for the compute shader, a buffer that we'll be writing to in the shader, a prefab, the number of prefabs we want, an array for the instanced prefabs, an array for the coordinate data. Any extra variables we want to pass over, eg time. On the compute shader side we need : To specify a read-write buffer, instead of a texture that we created in the previous post. The buffer will be of float3 type, which is how HLSL calls a vector3. That's actually it... Here's the Compute Shader code - #pragma kernel boxMove RWStructuredBuffer<float3> yesBlad; float time; [numthreads(64,1,1)] void boxMove (uint3 id : SV_DispatchThreadID) {     float xpos = (float)id.x;     float ypos = sin(id.x+time)*50;     float zpos = cos(id.x +time)* 50;    ...

 First make a compute shader - right click in the project window-  create shader, compute shader The default code will look as follows // Each #kernel tells which function to compile; you can have many kernels #pragma kernel CSMain // Create a RenderTexture with enableRandomWrite flag and set it // with cs.SetTexture RWTexture2D<float4> Result; [numthreads(8,8,1)] void CSMain (uint3 id : SV_DispatchThreadID) {     // TODO: insert actual code here!     Result[id.xy] = float4(id.x & id.y, (id.x & 15)/15.0, (id.y & 15)/15.0, 0.0); }   To keep things simple, lets just replace that last Result... line with    Result[id.xy]=float4(1,1,0,0);  This will make our shader produce a yellow colour. Note the #pragma kernel is called CSMain. This is basically the function name we'll be calling from the C# script.   To go with the compute shader, we need a C# script that assigns the shader to our geometry. Let's use a Qu...