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261 行
10 KiB
261 行
10 KiB
using System;
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namespace UnityEngine.Experimental.Rendering
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{
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public struct Frustum
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{
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public Plane[] planes; // Left, right, top, bottom, near, far
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public Vector3[] corners; // Positions of the 8 corners
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// The frustum will be camera-relative if given a camera-relative VP matrix.
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public static Frustum Create(Matrix4x4 viewProjMatrix, bool depth_0_1, bool reverseZ)
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{
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Frustum frustum = new Frustum();
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frustum.planes = new Plane[6];
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frustum.corners = new Vector3[8];
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GeometryUtility.CalculateFrustumPlanes(viewProjMatrix, frustum.planes);
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float nd = -1.0f;
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if (depth_0_1)
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{
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nd = 0.0f;
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// See "Fast Extraction of Viewing Frustum Planes" by Gribb and Hartmann.
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Vector3 f = new Vector3(viewProjMatrix.m20, viewProjMatrix.m21, viewProjMatrix.m22);
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float s = (float)(1.0 / Math.Sqrt(f.sqrMagnitude));
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Plane np = new Plane(s * f, s * viewProjMatrix.m23);
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frustum.planes[4] = np;
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}
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if (reverseZ)
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{
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Plane tmp = frustum.planes[4];
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frustum.planes[4] = frustum.planes[5];
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frustum.planes[5] = tmp;
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}
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Matrix4x4 invViewProjMatrix = viewProjMatrix.inverse;
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// Unproject 8 frustum points.
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frustum.corners[0] = invViewProjMatrix.MultiplyPoint(new Vector3(-1, -1, 1));
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frustum.corners[1] = invViewProjMatrix.MultiplyPoint(new Vector3(1, -1, 1));
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frustum.corners[2] = invViewProjMatrix.MultiplyPoint(new Vector3(-1, 1, 1));
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frustum.corners[3] = invViewProjMatrix.MultiplyPoint(new Vector3(1, 1, 1));
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frustum.corners[4] = invViewProjMatrix.MultiplyPoint(new Vector3(-1, -1, nd));
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frustum.corners[5] = invViewProjMatrix.MultiplyPoint(new Vector3(1, -1, nd));
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frustum.corners[6] = invViewProjMatrix.MultiplyPoint(new Vector3(-1, 1, nd));
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frustum.corners[7] = invViewProjMatrix.MultiplyPoint(new Vector3(1, 1, nd));
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return frustum;
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}
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} // struct Frustum
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[GenerateHLSL]
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public struct OrientedBBox
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{
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// 3 x float4 = 48 bytes.
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// TODO: pack the axes into 16-bit UNORM per channel, and consider a quaternionic representation.
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public Vector3 right;
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public float extentX;
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public Vector3 up;
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public float extentY;
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public Vector3 center;
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public float extentZ;
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public Vector3 forward { get { return Vector3.Cross(up, right); } }
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public static OrientedBBox Create(Transform t)
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{
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OrientedBBox obb = new OrientedBBox();
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Vector3 vecX = t.localToWorldMatrix.GetColumn(0);
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Vector3 vecY = t.localToWorldMatrix.GetColumn(1);
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Vector3 vecZ = t.localToWorldMatrix.GetColumn(2);
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obb.center = t.position;
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obb.right = vecX * (1.0f / vecX.magnitude);
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obb.up = vecY * (1.0f / vecY.magnitude);
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obb.extentX = 0.5f * vecX.magnitude;
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obb.extentY = 0.5f * vecY.magnitude;
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obb.extentZ = 0.5f * vecZ.magnitude;
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return obb;
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}
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} // struct OrientedBBox
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public static class GeometryUtils
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{
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// Returns 'true' if the OBB intersects (or is inside) the frustum, 'false' otherwise.
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public static bool Overlap(OrientedBBox obb, Frustum frustum, int numPlanes, int numCorners)
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{
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bool overlap = true;
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// Test the OBB against frustum planes. Frustum planes are inward-facing.
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// The OBB is outside if it's entirely behind one of the frustum planes.
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// See "Real-Time Rendering", 3rd Edition, 16.10.2.
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for (int i = 0; overlap && i < numPlanes; i++)
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{
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Vector3 n = frustum.planes[i].normal;
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float d = frustum.planes[i].distance;
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// Max projection of the half-diagonal onto the normal (always positive).
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float maxHalfDiagProj = obb.extentX * Mathf.Abs(Vector3.Dot(n, obb.right))
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+ obb.extentY * Mathf.Abs(Vector3.Dot(n, obb.up))
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+ obb.extentZ * Mathf.Abs(Vector3.Dot(n, obb.forward));
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// Positive distance -> center in front of the plane.
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// Negative distance -> center behind the plane (outside).
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float centerToPlaneDist = Vector3.Dot(n, obb.center) + d;
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// outside = maxHalfDiagProj < -centerToPlaneDist
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// outside = maxHalfDiagProj + centerToPlaneDist < 0
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// overlap = overlap && !outside
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overlap = overlap && (maxHalfDiagProj + centerToPlaneDist >= 0);
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}
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if (numCorners == 0) return overlap;
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// Test the frustum corners against OBB planes. The OBB planes are outward-facing.
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// The frustum is outside if all of its corners are entirely in front of one of the OBB planes.
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// See "Correct Frustum Culling" by Inigo Quilez.
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// We can exploit the symmetry of the box by only testing against 3 planes rather than 6.
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Plane[] planes = new Plane[3];
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planes[0].normal = obb.right;
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planes[0].distance = obb.extentX;
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planes[1].normal = obb.up;
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planes[1].distance = obb.extentY;
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planes[2].normal = obb.forward;
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planes[2].distance = obb.extentZ;
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for (int i = 0; overlap && i < 3; i++)
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{
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Plane plane = planes[i];
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// We need a separate counter for the "box fully inside frustum" case.
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bool outsidePos = true; // Positive normal
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bool outsideNeg = true; // Reversed normal
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// Merge 2 loops. Continue as long as all points are outside either plane.
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for (int j = 0; j < numCorners; j++)
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{
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float proj = Vector3.Dot(plane.normal, frustum.corners[j] - obb.center);
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outsidePos = outsidePos && (proj > plane.distance);
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outsideNeg = outsideNeg && (-proj > plane.distance);
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}
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overlap = overlap && !(outsidePos || outsideNeg);
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}
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return overlap;
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}
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public static readonly Matrix4x4 FlipMatrixLHSRHS = Matrix4x4.Scale(new Vector3(1, 1, -1));
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public static Vector4 Plane(Vector3 position, Vector3 normal)
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{
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var n = normal;
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var d = -Vector3.Dot(n, position);
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var plane = new Vector4(n.x, n.y, n.z, d);
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return plane;
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}
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public static Vector4 CameraSpacePlane(Matrix4x4 worldToCamera, Vector3 pos, Vector3 normal, float sideSign = 1, float clipPlaneOffset = 0)
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{
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var offsetPos = pos + normal * clipPlaneOffset;
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var cpos = worldToCamera.MultiplyPoint(offsetPos);
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var cnormal = worldToCamera.MultiplyVector(normal).normalized * sideSign;
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return new Vector4(cnormal.x, cnormal.y, cnormal.z, -Vector3.Dot(cpos, cnormal));
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}
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public static Matrix4x4 CalculateWorldToCameraMatrixRHS(Vector3 position, Quaternion rotation)
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{
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return Matrix4x4.Scale(new Vector3(1, 1, -1)) * Matrix4x4.TRS(position, rotation, Vector3.one).inverse;
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}
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public static Matrix4x4 CalculateWorldToCameraMatrixRHS(Transform transform)
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{
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return Matrix4x4.Scale(new Vector3(1, 1, -1)) * transform.localToWorldMatrix.inverse;
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}
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public static Matrix4x4 CalculateObliqueMatrix(Matrix4x4 sourceProjection, Vector4 clipPlane)
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{
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var projection = sourceProjection;
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var inversion = sourceProjection.inverse;
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var cps = new Vector4(
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Mathf.Sign(clipPlane.x),
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Mathf.Sign(clipPlane.y),
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1.0f,
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1.0f);
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var q = inversion * cps;
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var c = clipPlane * (2.0f / Vector4.Dot(clipPlane, q));
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projection[2] = c.x - projection[3];
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projection[6] = c.y - projection[7];
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projection[10] = c.z - projection[11];
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projection[14] = c.w - projection[15];
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return projection;
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}
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public static Matrix4x4 CalculateReflectionMatrix(Vector3 position, Vector3 normal)
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{
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return CalculateReflectionMatrix(Plane(position, normal.normalized));
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}
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public static Matrix4x4 CalculateReflectionMatrix(Vector4 plane)
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{
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var reflectionMat = new Matrix4x4();
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reflectionMat.m00 = (1F - 2F * plane[0] * plane[0]);
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reflectionMat.m01 = (-2F * plane[0] * plane[1]);
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reflectionMat.m02 = (-2F * plane[0] * plane[2]);
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reflectionMat.m03 = (-2F * plane[3] * plane[0]);
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reflectionMat.m10 = (-2F * plane[1] * plane[0]);
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reflectionMat.m11 = (1F - 2F * plane[1] * plane[1]);
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reflectionMat.m12 = (-2F * plane[1] * plane[2]);
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reflectionMat.m13 = (-2F * plane[3] * plane[1]);
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reflectionMat.m20 = (-2F * plane[2] * plane[0]);
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reflectionMat.m21 = (-2F * plane[2] * plane[1]);
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reflectionMat.m22 = (1F - 2F * plane[2] * plane[2]);
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reflectionMat.m23 = (-2F * plane[3] * plane[2]);
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reflectionMat.m30 = 0F;
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reflectionMat.m31 = 0F;
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reflectionMat.m32 = 0F;
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reflectionMat.m33 = 1F;
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return reflectionMat;
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}
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public static Matrix4x4 GetWorldToCameraMatrixLHS(this Camera camera)
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{
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return FlipMatrixLHSRHS * camera.worldToCameraMatrix;
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}
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public static Matrix4x4 GetProjectionMatrixLHS(this Camera camera)
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{
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return camera.projectionMatrix * FlipMatrixLHSRHS;
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}
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public static Matrix4x4 CalculateProjectionMatrix(Camera camera)
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{
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if (camera.orthographic)
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{
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var h = camera.orthographicSize;
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var w = camera.orthographicSize * camera.aspect;
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return Matrix4x4.Ortho(-w, w, -h, h, camera.nearClipPlane, camera.farClipPlane);
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}
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else
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return Matrix4x4.Perspective(camera.fieldOfView, camera.aspect, camera.nearClipPlane, camera.farClipPlane);
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}
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} // class GeometryUtils
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}
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