MaskPainter.cs

using UnityEngine;

public class MaskPainter : MonoBehaviour
{
    private const int DeformPassId = 0;
    private const int FlattenPassId = 1;
    private const int PaintPassId = 2;
    private const int PostprocessDepthPassId = 3;
    
    public Camera renderCamera;
    public int maskResolution = 256;
    public ComputeShader maskPainterShader;
    public Texture maskIntialDepth;
    public Material maskMaterial;
    public float flattenSpeed;

    public LayerMask paintCullingMask;
    public LayerMask flattenCullingMask;
    public LayerMask deformCullingMask;
    public LayerMask softEffectMask;
    
    public Color paintColor = Color.red;

    public RenderTexture paintDepthRenderTexture;
    public RenderTexture flattenDepthRenderTexture;
    public RenderTexture deformDepthRenderTexture;
    public RenderTexture effectDepthRenderTexture;
    
    private RenderTexture maskDepthTexture;
    private RenderTexture maskDepthPostprocessTexture;
    private RenderTexture maskColorTexture;

    private void Awake()
    {
        paintDepthRenderTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.Depth);
        flattenDepthRenderTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.Depth);
        deformDepthRenderTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.Depth);
        effectDepthRenderTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.Depth);

        maskDepthTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.ARGB32);
        maskDepthPostprocessTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.ARGB32);
        
        maskDepthTexture.enableRandomWrite = true;
        maskDepthPostprocessTexture.enableRandomWrite = true;
        
        maskDepthPostprocessTexture.Create();
        effectDepthRenderTexture.Create();
        deformDepthRenderTexture.Create();
        renderCamera.depthTextureMode = DepthTextureMode.Depth;

        renderCamera.enabled = false;

        maskPainterShader.SetInt("depthWidth", maskResolution);
        maskPainterShader.SetInt("depthHeight", maskResolution);
        
        // Should be in sync with mask position and material settings
        maskPainterShader.SetFloat("zNear", 0.10f / renderCamera.farClipPlane);
        maskPainterShader.SetFloat("zSize", renderCamera.farClipPlane - renderCamera.nearClipPlane);

        BindTextureToKernels("PaintDepthTexture", paintDepthRenderTexture);
        BindTextureToKernels("FlattenDepthTexture", flattenDepthRenderTexture);
        BindTextureToKernels("DeformDepthTexture", deformDepthRenderTexture);
        BindTextureToKernels("EffectDepthTexture", effectDepthRenderTexture);

        BindTextureToKernels("MaskDepthTexture", maskDepthTexture);
        BindTextureToKernels("MaskDepthPostprocessTexture", maskDepthPostprocessTexture);
        
        maskMaterial.SetTexture("_HeightMap", maskDepthPostprocessTexture);
        ResetColorTexture();
    }

    public void ResetMask()
    {
        Graphics.Blit(maskIntialDepth, maskDepthTexture);

        ResetColorTexture();
    }

    private void ResetColorTexture()
    {
        Destroy(maskColorTexture);
        
        maskColorTexture = new RenderTexture(maskResolution, maskResolution, 24, RenderTextureFormat.ARGB32);
        maskColorTexture.enableRandomWrite = true;
        maskColorTexture.Create();

        BindTextureToKernels("MaskColorTexture", maskColorTexture);
        maskMaterial.SetTexture("_ColorMap", maskColorTexture);
    }

    private void BindTextureToKernels(string name, RenderTexture tex)
    {
        var id = Shader.PropertyToID(name);
        maskPainterShader.SetTexture(DeformPassId, id, tex);
        maskPainterShader.SetTexture(FlattenPassId, id, tex);
        maskPainterShader.SetTexture(PaintPassId, id, tex);
        maskPainterShader.SetTexture(PostprocessDepthPassId, id, tex);
    }
    
    private void DispatchKernel(int kernelId)
    {
        maskPainterShader.Dispatch(kernelId, 
            Mathf.CeilToInt(maskResolution / 8f), 
            Mathf.CeilToInt(maskResolution / 8f),
            1);
    }

    private void LateUpdate()
    {
        UpdateShaderParams();

        PaintMask();
        DeformMask();
        FlattenMask();
        PostprocessMask();
    }

    private void UpdateShaderParams()
    {
        maskPainterShader.SetFloat("flattenSpeed", Time.deltaTime * flattenSpeed);
        maskPainterShader.SetFloat("postprocessSpeed", Time.deltaTime * 20f);
        maskPainterShader.SetVector("paintColor", paintColor);
    }

    private void DeformMask()
    {
        renderCamera.cullingMask = deformCullingMask;
        renderCamera.targetTexture = deformDepthRenderTexture;
        renderCamera.Render();
        DispatchKernel(DeformPassId);
    }

    private void FlattenMask()
    {
        renderCamera.cullingMask = flattenCullingMask;
        renderCamera.targetTexture = flattenDepthRenderTexture;
        renderCamera.Render();
        DispatchKernel(FlattenPassId);
    }

    private void PaintMask()
    {    
        renderCamera.cullingMask = paintCullingMask;
        renderCamera.targetTexture = paintDepthRenderTexture;
        renderCamera.Render();
        DispatchKernel(PaintPassId);
    }

    private void PostprocessMask()
    {
        renderCamera.cullingMask = softEffectMask;
        renderCamera.targetTexture = effectDepthRenderTexture;
        renderCamera.Render();
        DispatchKernel(PostprocessDepthPassId);
    }
}