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