我的截头剔除实施工作不正常;当我将相机向左旋转但不向右旋转时，会发生什么事情会剔除。如果我向后移动相机，它也将“剔除”，尽管物体消失并且未渲染的距离非常短 - 使用物体中心（球体）时约为6.0f个单位和相机计算距离的位置。上下移动/旋转并没有真正起作用。
我的投影距离很高：500.0f，我的近平面为0.1f。当然，降低/升高远平面似乎并不会影响剔除。
代码
这是平面计算代码：
void Frustum::UpdateCamParams( Camera* camera )
{
vec3 fartl, fartr, farbl, farbr;
vec3 neartl, neartr, nearbl, nearbr;
const vec3& camLook = camera->GetLook();
const vec3& camUp = camera->GetUp();
const vec3& camRight = camera->GetRight();
const vec3& camPos = camera->GetPosition();
const float zFar = camera->GetFarZ();
const float zNear = camera->GetNearZ();
float halfFarWidth = camera->GetFarWindowWidth() * 0.5f;
float halfFarHeight = camera->GetFarWindowHeight() * 0.5f;
float halfNearWidth = camera->GetNearWindowWidth() * 0.5f;
float halfNearHeight = camera->GetNearWindowHeight() * 0.5f;
const vec3& farClip = camPos + camLook * zFar;
fartl = farClip + ( camUp * halfFarHeight ) - ( camRight * halfFarWidth );
fartr = farClip + ( camUp * halfFarHeight ) + ( camRight * halfFarWidth );
farbl = farClip - ( camUp * halfFarHeight ) - ( camRight * halfFarWidth );
farbr = farClip - ( camUp * halfFarHeight ) + ( camRight * halfFarWidth );
const vec3& nearClip = camPos + camLook * zNear;
neartl = nearClip + ( camUp * halfNearHeight ) - ( camRight * halfNearWidth );
neartr = nearClip + ( camUp * halfNearHeight ) + ( camRight * halfNearWidth );
nearbl = nearClip - ( camUp * halfNearHeight ) - ( camRight * halfNearWidth );
nearbr = nearClip - ( camUp * halfNearHeight ) + ( camRight * halfNearWidth );
////viewRay = camLook - camPos;
// Points are set in a counter-clockwise order, for each plane
planes[ FRUST_LEFT ].points[ 0 ] = nearbl;
planes[ FRUST_LEFT ].points[ 1 ] = farbl;
planes[ FRUST_LEFT ].points[ 2 ] = fartl;
M_ComputePlane( &planes[ FRUST_LEFT ] );
planes[ FRUST_RIGHT ].points[ 0 ] = nearbr;
planes[ FRUST_RIGHT ].points[ 1 ] = farbr;
planes[ FRUST_RIGHT ].points[ 2 ] = fartr;
M_ComputePlane( &planes[ FRUST_RIGHT ] );
planes[ FRUST_TOP ].points[ 0 ] = neartl;
planes[ FRUST_TOP ].points[ 1 ] = neartr;
planes[ FRUST_TOP ].points[ 2 ] = fartr;
M_ComputePlane( &planes[ FRUST_TOP ] );
planes[ FRUST_BOTTOM ].points[ 0 ] = nearbl;
planes[ FRUST_BOTTOM ].points[ 1 ] = nearbr;
planes[ FRUST_BOTTOM ].points[ 2 ] = farbr;
M_ComputePlane( &planes[ FRUST_BOTTOM ] );
planes[ FRUST_FAR ].points[ 0 ] = farbl;
planes[ FRUST_FAR ].points[ 1 ] = farbr;
planes[ FRUST_FAR ].points[ 2 ] = fartr;
M_ComputePlane( &planes[ FRUST_FAR ] );
planes[ FRUST_NEAR ].points[ 0 ] = nearbl;
planes[ FRUST_NEAR ].points[ 1 ] = nearbr;
planes[ FRUST_NEAR ].points[ 2 ] = neartr;
M_ComputePlane( &planes[ FRUST_NEAR ] );
}
简而言之，首先计算远剪辑和近剪辑平面中心，然后计算两个平截头体边的四个角以允许planes数组内的点设置如下。 planes数组用于表示平截头体的6个边。
M_ComputePlane计算飞机的法线和原点距离d：
void M_ComputePlane( plane_t* p )
{
vec3 e1 = p->points[ 2 ] - p->points[ 1 ];
vec3 e3 = p->points[ 1 ] - p->points[ 0 ];
vec3 normal = glm::cross( e1, e3 );
p->normal = glm::length( normal ) > 1.0f ? glm::normalize( normal ) : normal;
p->d = glm::dot( p->points[ 0 ], p->normal );
}
以下是执行的交叉测试，每个测试都经过测试，基本上产生相同的结果：
/*
=============================
Frustum::BoundsInSphere
returns true in the event that the given center and radius
are within the view frustum
=============================
*/
bool Frustum::BoundsInSphere( const vec3& center, float radius )
{
for ( uint32_t i = 0; i < 6; ++i )
{
// center dot planes[ i ].normal = magnitude of projecting sphere center position onto plane normal
// plane[ i ].d = distance from origin to plane
float test = glm::dot( center, planes[ i ].normal ) + planes[ i ].d + radius;
if ( test <= 0 )
return false; // object is outside of this plane - reject!
}
return true;
}
/*
=============================
Frustum::BoundsInAABB_AllPoints
Tests each vertex of the AABB and only
returns false if all points are outside of one of
the frustum planes. Otherwise, the object
is considered renderable.
=============================
*/
bool Frustum::BoundsInAABB_AllPoints( const AABB& box )
{
for ( uint32_t i = 0; i < 6; ++i )
{
int out = 0;
for ( uint32_t k = 0; k < 8; ++k )
{
float test = glm::dot( box.Corner( k ), planes[ i ].normal ) + planes[ i ].d;
if ( test < 0 )
++out;
}
if ( out == 8 ) // all points rejected for this plane - bail
return false;
}
return true;
}
/*
=============================
Frustum::BoundsInAABB_Closest
Find the closest boint of the AABB
to frustum plane[ i ]. If that point
has a signed distance less than 0
to the plane, we reject it.
Otherwise, we continue to test with the farthest
point of the AABB to the given plane, and update
our intersection enum accordingly.
=============================
*/
bool Frustum::BoundsInAABB_Closest( const AABB& box, frustumPlane_t* intersection )
{
*intersection = FRUST_NONE;
for ( uint32_t i = 0; i < 6; ++i )
{
const vec3& positive = box.GetPointRelativeToNormal( planes[ i ].normal, true );
if ( M_SignedPlaneDistance( &planes[ i ], positive ) < 0 )
return false; // closest point is outside; reject.
const vec3& negative = box.GetPointRelativeToNormal( planes[ i ].normal, false );
if ( M_SignedPlaneDistance( &planes[ i ], negative ) < 0 )
*intersection = ( frustumPlane_t ) i;
}
return true;
}