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@nothke
Last active Mar 31, 2022
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using System.Collections.Generic;
using UnityEngine;
public static class ObjectPreviewer
{
struct Node
{
public Matrix4x4 transform;
public Mesh mesh;
public Material[] mats;
}
// Static cache
static List<MeshFilter> meshFiltersBuffer;
static List<Node> nodes;
/// <summary>
/// For performance reasons, the cache never deallocates.
/// So, call this to clear the cache only in the case the memory becomes a problem, such as with previewing objects with gigantic hierarchies.
/// (but even if they're gigantic it's quite unlikely it will be a problem)
/// </summary>
[RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
public static void ReloadCache()
{
meshFiltersBuffer = new List<MeshFilter>();
nodes = new List<Node>();
}
/// <summary>
/// Assigns object for rendering. Call this only once on preview object change. Pass null to clear the object.
/// </summary>
public static void SetObject(GameObject go)
{
nodes.Clear();
meshFiltersBuffer.Clear();
if (go == null)
return;
Matrix4x4 rootW2L = go.transform.worldToLocalMatrix;
// We need to scale in case the root has non 1,1,1 scale
Matrix4x4 rootScaleMatrix = Matrix4x4.Scale(go.transform.localScale);
go.transform.GetComponentsInChildren(meshFiltersBuffer);
foreach (var mf in meshFiltersBuffer)
{
Mesh mesh = mf.sharedMesh;
var mr = mf.GetComponent<MeshRenderer>();
if (mesh == null)
continue;
// Un-transform by root
Matrix4x4 matrix = rootW2L * mf.transform.localToWorldMatrix * rootScaleMatrix;
Material[] mats = null;
if (mr != null)
mats = mr.sharedMaterials;
nodes.Add(new Node()
{
mesh = mesh,
transform = matrix,
mats = mats,
});
}
}
/// <summary>
/// Renders the preview object set with SetObject(). Call this every frame you want the object to be drawn.
/// </summary>
/// <param name="overrideMaterial">The replacement material that the previews will be drawn with. If not assigned, it will use the original material.</param>
public static void Render(Vector3 position, Quaternion rotation, Vector3 scale, Material overrideMaterial = null, int renderLayer = 0)
{
Matrix4x4 previewTransform = Matrix4x4.TRS(position, rotation, scale);
foreach (var node in nodes)
{
for (int subMeshIndex = 0; subMeshIndex < node.mesh.subMeshCount; subMeshIndex++)
{
var mat = overrideMaterial != null ? overrideMaterial : node.mats[Mathf.Clamp(subMeshIndex, 0, node.mats.Length)];
Graphics.DrawMesh(node.mesh, previewTransform * node.transform, mat, renderLayer, null, subMeshIndex);
}
}
}
}
using UnityEngine;
public class ObjectPreviewerTest : MonoBehaviour
{
public GameObject testObject;
public Material replacementMaterial;
public int renderLayer = 0;
private void Start()
{
ObjectPreviewer.SetObject(testObject);
}
private void Update()
{
ObjectPreviewer.Render(transform.position, transform.rotation, transform.localScale, replacementMaterial, renderLayer);
}
}
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