/* ** Command & Conquer Renegade(tm) ** Copyright 2025 Electronic Arts Inc. ** ** This program is free software: you can redistribute it and/or modify ** it under the terms of the GNU General Public License as published by ** the Free Software Foundation, either version 3 of the License, or ** (at your option) any later version. ** ** This program is distributed in the hope that it will be useful, ** but WITHOUT ANY WARRANTY; without even the implied warranty of ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ** GNU General Public License for more details. ** ** You should have received a copy of the GNU General Public License ** along with this program. If not, see . */ /*********************************************************************************************** *** C O N F I D E N T I A L --- W E S T W O O D S T U D I O S *** *********************************************************************************************** * * * Project Name : WWMath * * * * $Archive:: /Commando/Code/wwmath/frustum.cpp $* * * * Author:: Greg Hjelstrom * * * * $Modtime:: 4/01/01 12:47p $* * * * $Revision:: 5 $* * * *---------------------------------------------------------------------------------------------* * Functions: * * FrustumClass::Init -- Initialize a frustum object * * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ #include "frustum.h" /*********************************************************************************************** * FrustumClass::Init -- Initialize a frustum object * * * * This function initializes a frustum from the description of a camera * * * * INPUT: * * camera - camera transform, note that the camera looks down the -Z axis * * vpmin - min corner of the z=-1.0 view plane (not necessarily the near clip plane) * * vpmax - max corner of the z=-1.0 view plane (not necessarily the near clip plane) * * znear - near clip plane (should be negative, negated if it is not) * * zfar - far clip plane (should be negative, negated if it is not) * * * * OUTPUT: * * * * WARNINGS: * * The vpmin and vpmax variables are the min and max of a view-plane at z=-1.0 * * * * * * HISTORY: * * 2/17/2000 gth : Created. * *=============================================================================================*/ void FrustumClass::Init ( const Matrix3D & camera, const Vector2 & vpmin, const Vector2 & vpmax, float znear, float zfar ) { int i; // Store the camera transform CameraTransform = camera; // Forward is negative Z in our viewspace coordinate system. // Just flip the sign if the user passed in positive values. if ((znear > 0.0f) && (zfar > 0.0f)) { znear = -znear; zfar = -zfar; } // Calculate the corners of the camera frustum. // Generate the camera-space frustum corners by linearly // extrapolating the viewplane to the near and far z clipping planes. // The camera frustum corners are defined in the following order: // When looking at the frustum from the position of the camera, the near four corners are // numbered: upper left 0, upper right 1, lower left 2, lower right 3. The far plane's // Frustum corners are numbered from 4 to 7 in an analogous fashion. // (remember: the camera space has x going to the right, y up and z backwards). Corners[0].Set(vpmin.X, vpmax.Y, 1.0); Corners[4] = Corners[0]; Corners[0] *= znear; Corners[4] *= zfar; Corners[1].Set(vpmax.X, vpmax.Y, 1.0); Corners[5] = Corners[1]; Corners[1] *= znear; Corners[5] *= zfar; Corners[2].Set(vpmin.X, vpmin.Y, 1.0); Corners[6] = Corners[2]; Corners[2] *= znear; Corners[6] *= zfar; Corners[3].Set(vpmax.X, vpmin.Y, 1.0); Corners[7] = Corners[3]; Corners[3] *= znear; Corners[7] *= zfar; // Transform the eight corners of the view frustum from camera space to world space. for (i = 0; i < 8; i++) { Matrix3D::Transform_Vector(CameraTransform, Corners[i], &(Corners[i])); } // Create the six frustum bounding planes from the eight corner Corners. // The bounding planes are oriented so that their normals point outward PlaneClass frustum_planes[6]; Planes[0].Set(Corners[0], Corners[3], Corners[1]); // near Planes[1].Set(Corners[0], Corners[5], Corners[4]); // bottom Planes[2].Set(Corners[0], Corners[6], Corners[2]); // right Planes[3].Set(Corners[2], Corners[7], Corners[3]); // top Planes[4].Set(Corners[1], Corners[7], Corners[5]); // left Planes[5].Set(Corners[4], Corners[7], Corners[6]); // far // find the bounding box of the entire frustum (may be used for sloppy quick rejection) BoundMin = BoundMax = Corners[0]; for (i=1; i<8;i++) { if (Corners[i].X < BoundMin.X) BoundMin.X = Corners[i].X; if (Corners[i].X > BoundMax.X) BoundMax.X = Corners[i].X; if (Corners[i].Y < BoundMin.Y) BoundMin.Y = Corners[i].Y; if (Corners[i].Y > BoundMax.Y) BoundMax.Y = Corners[i].Y; if (Corners[i].Z < BoundMin.Z) BoundMin.Z = Corners[i].Z; if (Corners[i].Z > BoundMax.Z) BoundMax.Z = Corners[i].Z; } }