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# csPlane3 Class Reference
[Geometry utilities]

A plane in 3D space. More...

`#include <csgeom/plane3.h>`

List of all members.

## Public Member Functions

float & | A ()
| Return the A component of this plane.
float | A () const
| Return the A component of this plane.
float & | B ()
| Return the B component of this plane.
float | B () const
| Return the B component of this plane.
float & | C ()
| Return the C component of this plane.
float | C () const
| Return the C component of this plane.
float | Classify (const csVector3 &pt) const
| Classify the given vector with regards to this plane.
bool | ClipPolygon (csVector3 *&pverts, int &num_verts, bool reversed=false)
| Clip the polygon in pverts (having num_verts vertices) to this plane.
| csPlane3 (const csVector3 &v2, const csVector3 &v3)
| Initialize the plane through 0 and the two given points.
| csPlane3 (const csVector3 &v1, const csVector3 &v2, const csVector3 &v3)
| Initialize the plane through the three given points.
| csPlane3 (float a, float b, float c, float d=0)
| Initialize the plane to the given components.
| csPlane3 (const csVector3 &plane_norm, float d=0)
| Initialize the plane with the given norm and D component.
| csPlane3 ()
| Initialize to the xy plane (0,0,1,0).
float & | D ()
| Return the D component of this plane.
float | D () const
| Return the D component of this plane.
csString | Description () const
| Return a textual representation of the plane in the form "aa,bb,cc,dd".
float | Distance (const csVector3 &pt) const
| Compute the distance from the given vector to this plane.
csVector3 | FindPoint () const
| Find a point on this plane.
const csVector3 & | GetNormal () const
| Return the normal of this plane.
void | Invert ()
| Reverses the direction of the plane while maintianing the plane itself.
const csVector3 & | Normal () const
| Return the normal vector of this plane.
csVector3 & | Normal ()
| Return the normal vector of this plane.
void | Normalize ()
| Normalizes the plane equation so that 'norm' is a unit vector.
void | Set (const csVector3 &v2, const csVector3 &v3)
| Initialize the plane through 0 and the two given points.
void | Set (const csVector3 &v1, const csVector3 &v2, const csVector3 &v3)
| Initialize the plane through the three given points.
void | Set (const csVector3 &normal, float d)
| Set the value of the plane using a normal and D component.
void | Set (float a, float b, float c, float d)
| Set the value of the four plane components.
void | SetOrigin (const csVector3 &p)
| Set one point ("origin") through which the plane goes.

## Static Public Member Functions

static float | Classify (float A, float B, float C, float D, const csVector3 &pt)
| This static function classifies a vector with regards to four given plane components.

## Public Attributes

float | DD
| The D component of the plane.
csVector3 | norm
| The normal vector (or the (A,B,C) components).

## Detailed Description

A plane in 3D space.

The plane is given by the equation AAx + BBy + CCz + DD = 0, Where (AA,BB,CC) is given by the vector 'norm'.

Definition at line 41 of file plane3.h.

## Constructor & Destructor Documentation

csPlane3::csPlane3 | ( |  | ) | `[inline]`

| Initialize to the xy plane (0,0,1,0). Definition at line 53 of file plane3.h.

csPlane3::csPlane3 | ( | const csVector3 & | plane_norm,
|  | float | d = `0`
| ) | `[inline]`

| Initialize the plane with the given norm and D component. Definition at line 58 of file plane3.h.

csPlane3::csPlane3 | ( | float | a,
|  | float | b,
|  | float | c,
|  | float | d = `0`
| ) | `[inline]`

| Initialize the plane to the given components. Definition at line 63 of file plane3.h.

csPlane3::csPlane3 | ( | const csVector3 & | v1,
|  | const csVector3 & | v2,
|  | const csVector3 & | v3
| ) |

| Initialize the plane through the three given points. If the plane is expressed as (N,D) with N the A,B,C components of the plane then this will initialize the plane to (N',-N'*v1) with N' equal to (v1-v2)%(v1-v3).

csPlane3::csPlane3 | ( | const csVector3 & | v2,
|  | const csVector3 & | v3
| ) | `[inline]`

| Initialize the plane through 0 and the two given points. If the plane is expressed as (N,D) with N the A,B,C components of the plane then this will initialize the plane to (v2v3,0). Definition at line 78 of file plane3.h.

## Member Function Documentation

float& csPlane3::A | ( |  | ) | `[inline]`

| Return the A component of this plane. Definition at line 98 of file plane3.h.

float csPlane3::A | ( |  | ) | const`[inline]`

| Return the A component of this plane. Definition at line 89 of file plane3.h. References csVector3::x.

float& csPlane3::B | ( |  | ) | `[inline]`

| Return the B component of this plane. Definition at line 100 of file plane3.h.

float csPlane3::B | ( |  | ) | const`[inline]`

| Return the B component of this plane. Definition at line 91 of file plane3.h.

float& csPlane3::C | ( |  | ) | `[inline]`

| Return the C component of this plane. Definition at line 102 of file plane3.h.

float csPlane3::C | ( |  | ) | const`[inline]`

| Return the C component of this plane. Definition at line 93 of file plane3.h.

static float csPlane3::Classify | ( | float | A,
|  | float | B,
|  | float | C,
|  | float | D,
|  | const csVector3 & | pt
| ) | `[inline, static]`

| This static function classifies a vector with regards to four given plane components. This will calculate and return A*pt.x+B*pt.y+C*pt.z+D. Definition at line 160 of file plane3.h. References csVector3::x, csVector3::y, and csVector3::z.

float csPlane3::Classify | ( | const csVector3 & | pt | ) | const`[inline]`

Classify the given vector with regards to this plane.

If the plane is expressed as (N,D) with N the A,B,C components of the plane then this will calculate and return N*pt+D. Note that in the Crystal Space engine this function will return negative if used on the visible side of a polygon. i.e. if you take the world space plane of the polygon, then Classify() will return a negative value if the camera is located at a point from which you can see the polygon. Back-face culling will make the polygon invisible on the other side.

Definition at line 154 of file plane3.h.

Referenced by csSquaredDist::PointPlane(), and csMath3::Visible().

bool csPlane3::ClipPolygon | ( | csVector3 *& | pverts,
|  | int & | num_verts,
|  | bool | reversed = `false`
| ) |

Clip the polygon in pverts (having num_verts vertices) to this plane.

The vertices are expected in camera space. Method returns true if there is something visible, false otherwise. Note that this function returns a pointer to a static array in csPlane3. The contents of this array will only be valid until the next call to ClipPolygon. Normally this function will consider the polygon visible if it is on the negative side of the plane (Classify()). If 'reversed' is set to true then the positive side will be used instead.

float& csPlane3::D | ( |  | ) | `[inline]`

| Return the D component of this plane. Definition at line 104 of file plane3.h.

float csPlane3::D | ( |  | ) | const`[inline]`

| Return the D component of this plane. Definition at line 95 of file plane3.h.

csString csPlane3::Description | ( |  | ) | const

| Return a textual representation of the plane in the form "aa,bb,cc,dd".

float csPlane3::Distance | ( | const csVector3 & | pt | ) | const`[inline]`

| Compute the distance from the given vector to this plane. This function assumes that 'norm' is a unit vector. If not, the function returns distance times the magnitude of 'norm'. This function corresponds exactly to the absolute value of Classify(). Definition at line 172 of file plane3.h. References ABS.

csVector3 csPlane3::FindPoint | ( |  | ) | const

| Find a point on this plane.

const csVector3& csPlane3::GetNormal | ( |  | ) | const`[inline]`

| Return the normal of this plane. Definition at line 107 of file plane3.h.

void csPlane3::Invert | ( |  | ) | `[inline]`

| Reverses the direction of the plane while maintianing the plane itself. This will basically reverse the result of Classify(). Definition at line 179 of file plane3.h.

const csVector3& csPlane3::Normal | ( |  | ) | const`[inline]`

| Return the normal vector of this plane. Definition at line 86 of file plane3.h.

csVector3& csPlane3::Normal | ( |  | ) | `[inline]`

| Return the normal vector of this plane. Definition at line 84 of file plane3.h.

void csPlane3::Normalize | ( |  | ) | `[inline]`

| Normalizes the plane equation so that 'norm' is a unit vector. Definition at line 184 of file plane3.h.

void csPlane3::Set | ( | const csVector3 & | v2,
|  | const csVector3 & | v3
| ) | `[inline]`

| Initialize the plane through 0 and the two given points. If the plane is expressed as (N,D) with N the A,B,C components of the plane then this will initialize the plane to (v2v3,0). Definition at line 130 of file plane3.h.

void csPlane3::Set | ( | const csVector3 & | v1,
|  | const csVector3 & | v2,
|  | const csVector3 & | v3
| ) |

| Initialize the plane through the three given points. If the plane is expressed as (N,D) with N the A,B,C components of the plane then this will initialize the plane to (N',-N'*v1) with N' equal to (v1-v2)%(v1-v3).

void csPlane3::Set | ( | const csVector3 & | normal,
|  | float | d
| ) | `[inline]`

| Set the value of the plane using a normal and D component. Definition at line 114 of file plane3.h.

void csPlane3::Set | ( | float | a,
|  | float | b,
|  | float | c,
|  | float | d
| ) | `[inline]`

| Set the value of the four plane components. Definition at line 110 of file plane3.h.

void csPlane3::SetOrigin | ( | const csVector3 & | p | ) | `[inline]`

| Set one point ("origin") through which the plane goes. This is equal to setting DD = -N'*p where N' is the normal Definition at line 139 of file plane3.h.

## Member Data Documentation

float csPlane3::DD

| The D component of the plane. Definition at line 48 of file plane3.h. Referenced by csMath3::PlanesEqual().

csVector3 csPlane3::norm

| The normal vector (or the (A,B,C) components). Definition at line 45 of file plane3.h. Referenced by csMath3::PlanesEqual().

The documentation for this class was generated from the following file:

- csgeom/plane3.h