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【光照】UnityURP[光照贴图]GPU instancing在静态动态物体上的应用

news 2025/10/10 10:36:25

【从UnityURP开始探索游戏渲染】专栏-直达

静态物体GPU Instancing与光照贴图

‌技术要点‌：

‌静态标记‌：物体需标记为Batching Static，但需禁用静态合批以避免与GPU Instancing冲突。
‌光照贴图绑定‌：通过LightmapIndex和LightmapScaleOffset手动绑定烘焙结果。
‌Shader适配‌：需在着色器中添加实例化支持与光照贴图采样逻辑。

‌示例代码‌：

StaticInstancingExample.cs

using UnityEngine;[ExecuteAlways]
public class StaticInstancingExample : MonoBehaviour {public Mesh mesh;public Material material;public int instanceCount = 100;private Matrix4x4[] matrices;private Vector4[] lightmapOffsets;void Start() {// 生成实例变换矩阵matrices = new Matrix4x4[instanceCount];lightmapOffsets = new Vector4[instanceCount];for (int i = 0; i < instanceCount; i++) {Vector3 pos = Random.insideUnitSphere * 10f;matrices[i] = Matrix4x4.TRS(pos, Quaternion.identity, Vector3.one);// 模拟不同光照贴图偏移（需与烘焙数据匹配）lightmapOffsets[i] = new Vector4(1, 1, i % 2 * 0.5f, i / 2 * 0.5f);}}void Update() {MaterialPropertyBlock props = new MaterialPropertyBlock();props.SetVectorArray("_LightmapST", lightmapOffsets); // 传递光照贴图UV偏移Graphics.DrawMeshInstanced(mesh, 0, material, matrices, instanceCount, props);}
}

‌实现说明‌：

使用MaterialPropertyBlock传递每实例的光照贴图UV偏移参数。
着色器中需声明UNITY_LIGHTMAP_ON宏并采样unity_Lightmap纹理。

动态物体GPU Instancing与光照探针

‌技术要点‌：

‌光照探针替代‌：动态物体依赖Light Probes获取间接光照。
‌混合光源支持‌：光源设为Mixed模式，静态阴影烘焙到光照贴图，动态物体接收实时阴影。
‌实例化属性扩展‌：通过MaterialPropertyBlock传递探针数据。

‌示例代码‌：

DynamicInstancingExample.cs

using UnityEngine;public class DynamicInstancingExample : MonoBehaviour {public Mesh mesh;public Material material;public int instanceCount = 100;private Matrix4x4[] matrices;void Start() {matrices = new Matrix4x4[instanceCount];for (int i = 0; i < instanceCount; i++) {Vector3 pos = Random.insideUnitSphere * 10f;matrices[i] = Matrix4x4.TRS(pos, Quaternion.identity, Vector3.one);}}void Update() {MaterialPropertyBlock props = new MaterialPropertyBlock();// 为每个实例设置光照探针数据LightProbes.GetInterpolatedProbe(transform.position, null, out var probe);props.AddVector("_LightProbeData", new Vector4(probe.occlusion, 0, 0, 0));Graphics.DrawMeshInstanced(mesh, 0, material, matrices, instanceCount, props);}
}