58 lines
2.2 KiB
C
58 lines
2.2 KiB
C
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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
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// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <Jolt/Geometry/Plane.h>
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#include <Jolt/Geometry/AABox.h>
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/// A camera frustum containing of 6 planes (left, right, top, bottom, near, far) pointing inwards
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class [[nodiscard]] Frustum
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{
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public:
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/// Empty constructor
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Frustum() = default;
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/// Construct frustum from position, forward, up, field of view x and y and near plane.
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/// Note that inUp does not need to be perpendicular to inForward but cannot be collinear.
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inline Frustum(Vec3Arg inPosition, Vec3Arg inForward, Vec3Arg inUp, float inFOVX, float inFOVY, float inNear)
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{
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Vec3 right = inForward.Cross(inUp).Normalized();
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Vec3 up = right.Cross(inForward).Normalized(); // Calculate the real up vector (inUp does not need to be perpendicular to inForward)
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// Near plane
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mPlanes[0] = Plane::sFromPointAndNormal(inPosition + inNear * inForward, inForward);
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// Top and bottom planes
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mPlanes[1] = Plane::sFromPointAndNormal(inPosition, Mat44::sRotation(right, 0.5f * inFOVY) * -up);
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mPlanes[2] = Plane::sFromPointAndNormal(inPosition, Mat44::sRotation(right, -0.5f * inFOVY) * up);
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// Left and right planes
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mPlanes[3] = Plane::sFromPointAndNormal(inPosition, Mat44::sRotation(up, 0.5f * inFOVX) * right);
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mPlanes[4] = Plane::sFromPointAndNormal(inPosition, Mat44::sRotation(up, -0.5f * inFOVX) * -right);
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}
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/// Test if frustum overlaps with axis aligned box. Note that this is a conservative estimate and can return true if the
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/// frustum doesn't actually overlap with the box. This is because we only test the plane axis as separating axis
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/// and skip checking the cross products of the edges of the frustum
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inline bool Overlaps(const AABox &inBox) const
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{
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// Loop over all frustum planes
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for (const Plane &p : mPlanes)
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{
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// Get support point (the maximum extent) in the direction of our normal
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Vec3 support = inBox.GetSupport(p.GetNormal());
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// If this is behind our plane, the box is not inside the frustum
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if (p.SignedDistance(support) < 0.0f)
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return false;
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}
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return true;
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}
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private:
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Plane mPlanes[5]; ///< Planes forming the frustum
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};
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