168 lines
3.3 KiB
C++
168 lines
3.3 KiB
C++
/**
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* =========================================================================
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* File : Frustum.cpp
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* Project : 0 A.D.
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* Description : CFrustum is a collection of planes which define
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* a viewing space.
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* =========================================================================
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*/
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/*
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Usually associated with the camera, there are 6 planes which define the
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view pyramid. But we allow more planes per frustum which may be used for
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portal rendering, where a portal may have 3 or more edges.
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*/
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#include "precompiled.h"
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#include "Frustum.h"
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#include "maths/Bound.h"
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#include "maths/MathUtil.h"
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CFrustum::CFrustum ()
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{
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m_NumPlanes = 0;
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}
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CFrustum::~CFrustum ()
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{
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}
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void CFrustum::SetNumPlanes (int num)
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{
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m_NumPlanes = num;
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//clip it
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if (m_NumPlanes >= MAX_NUM_FRUSTUM_PLANES)
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m_NumPlanes = MAX_NUM_FRUSTUM_PLANES-1;
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else if (m_NumPlanes < 0)
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m_NumPlanes = 0;
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}
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bool CFrustum::IsPointVisible (const CVector3D &point) const
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{
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PLANESIDE Side;
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for (int i=0; i<m_NumPlanes; i++)
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{
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Side = m_aPlanes[i].ClassifyPoint (point);
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if (Side == PS_BACK)
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return false;
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}
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return true;
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}
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bool CFrustum::DoesSegmentIntersect(const CVector3D& startRef, const CVector3D &endRef)
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{
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CVector3D start = startRef;
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CVector3D end = endRef;
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if(IsPointVisible(start) || IsPointVisible(end))
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return true;
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CVector3D intersect;
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for ( int i = 0; i<m_NumPlanes; ++i )
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{
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if ( m_aPlanes[i].FindLineSegIntersection(start, end, &intersect) )
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{
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if ( IsPointVisible( intersect ) )
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return true;
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}
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}
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return false;
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}
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bool CFrustum::IsSphereVisible (const CVector3D ¢er, float radius) const
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{
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for (int i=0; i<m_NumPlanes; i++)
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{
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float Dist = m_aPlanes[i].DistanceToPlane (center);
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//is it behind the plane
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if (Dist < 0)
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{
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//if non of it falls in front its outside the
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//frustum
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if (-Dist > radius)
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return false;
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}
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}
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return true;
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}
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bool CFrustum::IsBoxVisible (const CVector3D &position,const CBound &bounds) const
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{
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//basically for every plane we calculate the furthest point
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//in the box to that plane. If that point is beyond the plane
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//then the box is not visible
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CVector3D FarPoint;
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PLANESIDE Side;
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CVector3D Min = position+bounds[0];
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CVector3D Max = position+bounds[1];
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for (int i=0; i<m_NumPlanes; i++)
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{
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if (m_aPlanes[i].m_Norm.X > 0.0f)
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{
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if (m_aPlanes[i].m_Norm.Y > 0.0f)
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{
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if (m_aPlanes[i].m_Norm.Z > 0.0f)
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{
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FarPoint.X = Max.X; FarPoint.Y = Max.Y; FarPoint.Z = Max.Z;
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}
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else
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{
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FarPoint.X = Max.X; FarPoint.Y = Max.Y; FarPoint.Z = Min.Z;
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}
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}
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else
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{
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if (m_aPlanes[i].m_Norm.Z > 0.0f)
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{
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FarPoint.X = Max.X; FarPoint.Y = Min.Y; FarPoint.Z = Max.Z;
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}
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else
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{
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FarPoint.X = Max.X; FarPoint.Y = Min.Y; FarPoint.Z = Min.Z;
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}
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}
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}
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else
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{
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if (m_aPlanes[i].m_Norm.Y > 0.0f)
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{
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if (m_aPlanes[i].m_Norm.Z > 0.0f)
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{
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FarPoint.X = Min.X; FarPoint.Y = Max.Y; FarPoint.Z = Max.Z;
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}
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else
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{
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FarPoint.X = Min.X; FarPoint.Y = Max.Y; FarPoint.Z = Min.Z;
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}
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}
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else
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{
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if (m_aPlanes[i].m_Norm.Z > 0.0f)
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{
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FarPoint.X = Min.X; FarPoint.Y = Min.Y; FarPoint.Z = Max.Z;
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}
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else
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{
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FarPoint.X = Min.X; FarPoint.Y = Min.Y; FarPoint.Z = Min.Z;
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}
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}
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}
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Side = m_aPlanes[i].ClassifyPoint (FarPoint);
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if (Side == PS_BACK)
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return false;
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}
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return true;
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}
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