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/* Copyright (C) 2021 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. 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 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
/*
Usually associated with the camera, there are 6 planes which define the
view pyramid. But we allow more planes per frustum which may be used for
portal rendering, where a portal may have 3 or more edges.
*/
#include "precompiled.h"
#include "Frustum.h"
#include "maths/BoundingBoxAligned.h"
#include "maths/MathUtil.h"
#include "maths/Matrix3D.h"
CFrustum::CFrustum()
{
m_NumPlanes = 0;
}
CFrustum::~CFrustum()
{
}
void CFrustum::SetNumPlanes(size_t num)
{
m_NumPlanes = num;
if (m_NumPlanes >= MAX_NUM_FRUSTUM_PLANES)
{
debug_warn(L"CFrustum::SetNumPlanes: Too many planes");
m_NumPlanes = MAX_NUM_FRUSTUM_PLANES - 1;
}
}
void CFrustum::AddPlane(const CPlane& plane)
{
if (m_NumPlanes >= MAX_NUM_FRUSTUM_PLANES)
{
debug_warn(L"CFrustum::AddPlane: Too many planes");
return;
}
m_Planes[m_NumPlanes++] = plane;
}
void CFrustum::Transform(const CMatrix3D& m)
{
for (size_t i = 0; i < m_NumPlanes; ++i)
{
CVector3D n = m.Rotate(m_Planes[i].m_Norm);
CVector3D p = m.Transform(m_Planes[i].m_Norm * -m_Planes[i].m_Dist);
m_Planes[i].Set(n, p);
m_Planes[i].Normalize();
}
}
bool CFrustum::IsPointVisible(const CVector3D& point) const
{
for (size_t i = 0; i < m_NumPlanes; ++i)
{
if (m_Planes[i].IsPointOnBackSide(point))
return false;
}
return true;
}
bool CFrustum::DoesSegmentIntersect(const CVector3D& startRef, const CVector3D& endRef) const
{
CVector3D start = startRef;
CVector3D end = endRef;
if (IsPointVisible(start) || IsPointVisible(end))
return true;
CVector3D intersect;
for (size_t i = 0; i < m_NumPlanes; ++i)
{
if (m_Planes[i].FindLineSegIntersection(start, end, &intersect))
{
if (IsPointVisible(intersect))
return true;
}
}
return false;
}
bool CFrustum::IsSphereVisible(const CVector3D& center, float radius) const
{
for (size_t i = 0; i < m_NumPlanes; ++i)
{
// If none of the sphere is in front of the plane, then
// it is outside the frustum.
if (-m_Planes[i].DistanceToPlane(center) > radius)
return false;
}
return true;
}
bool CFrustum::IsBoxVisible(const CVector3D& position, const CBoundingBoxAligned& bounds) const
{
// Basically for every plane we calculate the furthest point
// in the box to that plane. If that point is beyond the plane
// then the box is not visible.
CVector3D farPoint;
CVector3D minPoint = position + bounds[0];
CVector3D maxPoint = position + bounds[1];
for (size_t i = 0; i < m_NumPlanes; ++i)
{
farPoint.X = m_Planes[i].m_Norm.X > 0.0f ? maxPoint.X : minPoint.X;
farPoint.Y = m_Planes[i].m_Norm.Y > 0.0f ? maxPoint.Y : minPoint.Y;
farPoint.Z = m_Planes[i].m_Norm.Z > 0.0f ? maxPoint.Z : minPoint.Z;
if (m_Planes[i].IsPointOnBackSide(farPoint))
return false;
}
return true;
}
bool CFrustum::IsBoxVisible(const CBoundingBoxAligned& bounds) const
{
// Same as the previous one, but with the position = (0, 0, 0).
CVector3D farPoint;
for (size_t i = 0; i < m_NumPlanes; ++i)
{
farPoint.X = m_Planes[i].m_Norm.X > 0.0f ? bounds[1].X : bounds[0].X;
farPoint.Y = m_Planes[i].m_Norm.Y > 0.0f ? bounds[1].Y : bounds[0].Y;
farPoint.Z = m_Planes[i].m_Norm.Z > 0.0f ? bounds[1].Z : bounds[0].Z;
if (m_Planes[i].IsPointOnBackSide(farPoint))
return false;
}
return true;
}
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