阴影纹理判断深度那些我们都懂。我的疑惑是对于平行光，如何确定阴影贴图要覆盖的范围。
豆包回答：
左右 / 上下范围：由Shadow Distance和主相机的视场角决定，以主相机为中心，向平行光方向扩展出一个覆盖主相机视锥在Shadow Distance内所有区域的立方体，确保主相机能看到的范围内，阴影都能被正确生成。
我感觉就是对场景的所有模型都判断深度，对于一个平行光方向，只用生成一次阴影纹理就能一直使用。如果转动光源，就会看见右下角有Global illumination processing，可能就是在重新生成ShadowMap。
豆包提供了这个脚本，用于标识平行光源阴影视锥。
using UnityEngine; using UnityEditor; [RequireComponent(typeof(Light))] public class DirectionalShadowFrustumVisualizer : MonoBehaviour { [Header("可视化设置")] [Tooltip("视锥线条颜色")] public Color frustumColor = Color.cyan; [Tooltip("线条宽度（仅Scene视图生效）")] public float lineWidth = 2f; private Light _dirLight; private Camera _mainCamera; // 视锥的8个顶点 private Vector3[] _frustumCorners = new Vector3[8]; private void OnEnable() { _dirLight = GetComponent<Light>(); // 校验是否为平行光 if (_dirLight.type != LightType.Directional) { Debug.LogError("该脚本仅支持平行光！"); enabled = false; return; } _mainCamera = Camera.main; } // Scene视图绘制视锥 private void OnDrawGizmos() { if (!_dirLight || !_mainCamera) return; // 获取全局Shadow Distance float shadowDistance = QualitySettings.shadowDistance; // 获取平行光的阴影近裁剪面 float shadowNearPlane = _dirLight.shadowNearPlane; // 1. 计算主相机在Shadow Distance范围内的视锥投影边界 CalculateMainCameraFrustumBounds(shadowDistance, out Vector3 camFrustumMin, out Vector3 camFrustumMax); // 2. 计算平行光虚拟相机的正交视锥参数 Vector3 lightDir = _dirLight.transform.forward; // 视锥中心：主相机位置 + 平行光方向 * 阴影距离的一半 Vector3 frustumCenter = _mainCamera.transform.position + lightDir * shadowDistance * 0.5f; // 视锥尺寸：基于主相机视锥的宽度、高度，以及阴影近/远裁剪面的距离 Vector3 frustumSize = new Vector3( camFrustumMax.x - camFrustumMin.x, camFrustumMax.y - camFrustumMin.y, shadowDistance - shadowNearPlane ); // 3. 计算视锥的8个顶点 BuildFrustumCorners(frustumCenter, lightDir, frustumSize, shadowNearPlane); // 4. 绘制视锥线条 Gizmos.color = frustumColor; Handles.color = frustumColor; //Handles.lineThickness = lineWidth; // 绘制视锥的12条边 DrawLine(0, 1); DrawLine(1, 3); DrawLine(3, 2); DrawLine(2, 0); DrawLine(4, 5); DrawLine(5, 7); DrawLine(7, 6); DrawLine(6, 4); DrawLine(0, 4); DrawLine(1, 5); DrawLine(2, 6); DrawLine(3, 7); } // 计算主相机在指定距离下的视锥投影边界 private void CalculateMainCameraFrustumBounds(float distance, out Vector3 min, out Vector3 max) { float halfFOV = _mainCamera.fieldOfView * 0.5f * Mathf.Deg2Rad; float aspect = _mainCamera.aspect; float halfHeight = Mathf.Tan(halfFOV) * distance; float halfWidth = halfHeight * aspect; min = new Vector3(-halfWidth, -halfHeight, distance); max = new Vector3(halfWidth, halfHeight, distance); // 转换到世界空间 min = _mainCamera.transform.TransformVector(min); max = _mainCamera.transform.TransformVector(max); } // 构建正交视锥的8个顶点 private void BuildFrustumCorners(Vector3 center, Vector3 lightDir, Vector3 size, float nearPlane) { Vector3 halfSize = size * 0.5f; Vector3 up = Vector3.up; Vector3 right = Vector3.Cross(lightDir, up).normalized; up = Vector3.Cross(right, lightDir).normalized; // 近裁剪面4个顶点 _frustumCorners[0] = center - right * halfSize.x - up * halfSize.y - lightDir * (halfSize.z - nearPlane); _frustumCorners[1] = center + right * halfSize.x - up * halfSize.y - lightDir * (halfSize.z - nearPlane); _frustumCorners[2] = center - right * halfSize.x + up * halfSize.y - lightDir * (halfSize.z - nearPlane); _frustumCorners[3] = center + right * halfSize.x + up * halfSize.y - lightDir * (halfSize.z - nearPlane); // 远裁剪面4个顶点 _frustumCorners[4] = center - right * halfSize.x - up * halfSize.y + lightDir * halfSize.z; _frustumCorners[5] = center + right * halfSize.x - up * halfSize.y + lightDir * halfSize.z; _frustumCorners[6] = center - right * halfSize.x + up * halfSize.y + lightDir * halfSize.z; _frustumCorners[7] = center + right * halfSize.x + up * halfSize.y + lightDir * halfSize.z; } // 绘制单条线段 private void DrawLine(int indexA, int indexB) { Handles.DrawLine(_frustumCorners[indexA], _frustumCorners[indexB]); } }动了一下相机，视锥会跟着变化，规则挺复杂。
