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StelProjector Class Referenceabstract

Provide the main interface to all operations of projecting coordinates from sky to screen. More...

#include <StelProjector.hpp>

Data Structures

class  Mat4dTransform
 
class  ModelViewTranform
 Allows to define non linear operations in addition to the standard linear (Matrix 4d) ModelView transformation. More...
 
struct  StelProjectorParams
 Contains all the param needed to initialize a StelProjector. More...
 

Public Types

enum  StelProjectorMaskType { MaskNone , MaskDisk }
 Define viewport mask types. More...
 
typedef QSharedPointer< ModelViewTranformModelViewTranformP
 Shared pointer on a ModelViewTranform instance (implement reference counting)
 

Public Member Functions

virtual ~StelProjector ()
 Destructor.
 
virtual QString getNameI18 () const =0
 Get a human-readable name for this projection type.
 
virtual QString getDescriptionI18 () const
 Get a human-readable short description for this projection type.
 
QString getHtmlSummary () const
 Get a HTML version of the short description for this projection type.
 
virtual float getMaxFov () const =0
 Get the maximum FOV aperture in degree.
 
virtual bool forward (Vec3f &v) const =0
 Apply the transformation in the forward direction in place. More...
 
virtual bool backward (Vec3d &v) const =0
 Apply the transformation in the backward projection in place.
 
virtual float deltaZoom (float fov) const
 Return the small zoom increment to use at the given FOV for nice movements.
 
virtual QByteArray getForwardTransformShader () const =0
 Returns GLSL code that can be used in a shader to implement forward transformation.
 
virtual void setForwardTransformUniforms (QOpenGLShaderProgram &program) const
 Sets the necessary uniforms so that the shader returned by getForwardTransformShader can work.
 
virtual QByteArray getBackwardTransformShader () const =0
 Returns GLSL code that can be used in a shader to implement backward transformation.
 
virtual void setBackwardTransformUniforms (QOpenGLShaderProgram &program) const
 Sets the necessary uniforms so that the shader returned by getBackwardTransformShader can work.
 
bool intersectViewportDiscontinuity (const Vec3d &p1, const Vec3d &p2) const
 Determine whether a great circle connection p1 and p2 intersects with a projection discontinuity. More...
 
bool intersectViewportDiscontinuity (const SphericalCap &cap) const
 
virtual float fovToViewScalingFactor (float fov) const
 Convert a Field Of View radius value in radians in ViewScalingFactor (used internally)
 
virtual float viewScalingFactorToFov (float vsf) const
 Convert a ViewScalingFactor value (used internally) in Field Of View radius in radians.
 
bool getFlagGravityLabels () const
 Get the current state of the flag which decides whether to arrange labels so that they are aligned with the bottom of a 2d screen, or a 3d dome.
 
const Vec4igetViewport () const
 Get the lower left corner of the viewport and the width, height.
 
Vector2< qreal > getViewportCenter () const
 Get the center of the viewport relative to the lower left corner of the screen.
 
Vector2< qreal > getViewportCenterOffset () const
 
int getViewportPosX () const
 Get the horizontal viewport offset in pixels.
 
int getViewportPosY () const
 Get the vertical viewport offset in pixels.
 
int getViewportWidth () const
 Get the viewport width in pixels.
 
int getViewportHeight () const
 Get the viewport height in pixels.
 
qreal getDevicePixelsPerPixel () const
 Get the number of device pixels per "Device Independent Pixels" (value is usually 1, but 2 for mac retina screens).
 
SphericalRegionP getViewportConvexPolygon (float marginX=0., float marginY=0.) const
 Return a convex polygon on the sphere which includes the viewport in the current frame. More...
 
const SphericalCapgetBoundingCap () const
 Return a SphericalCap containing the whole viewport.
 
float getPixelPerRadAtCenter () const
 Get size of a radian in pixels at the center of the viewport disk.
 
float getFov () const
 Get the current FOV diameter in degrees.
 
bool needGlFrontFaceCW () const
 Get whether front faces need to be oriented in the clockwise direction.
 
bool checkInViewport (const Vec3d &pos) const
 Check to see if a 2d position is inside the viewport. More...
 
bool checkInViewport (const Vec3f &pos) const
 Check to see if a 2d position is inside the viewport. More...
 
Vec3d viewPortIntersect (const Vec3d &p1, const Vec3d &p2) const
 Return the position where the 2 2D point p1 and p2 cross the viewport edge P1 must be inside the viewport and P2 outside (check with checkInViewport() before calling this method)
 
bool project (const Vec3d &v, Vec3d &win) const
 Project the vector v from the current frame into the viewport. More...
 
bool project (const Vec3f &v, Vec3f &win) const
 Project the vector v from the current frame into the viewport. More...
 
bool project (const Vec3d &v, Vec3f &win) const
 Project the vector v from the current frame into the viewport. More...
 
virtual void project (int n, const Vec3d *in, Vec3f *out)
 
virtual void project (int n, const Vec3f *in, Vec3f *out)
 
bool projectInPlace (Vec3d &vd) const
 Project the vector v from the current frame into the viewport. More...
 
bool projectInPlace (Vec3f &v) const
 Project the vector v from the current frame into the viewport. More...
 
bool projectCheck (const Vec3d &v, Vec3d &win) const
 Project the vector v from the current frame into the viewport. More...
 
bool projectCheck (const Vec3f &v, Vec3f &win) const
 Project the vector v from the current frame into the viewport. More...
 
bool unProject (const Vec3d &win, Vec3d &v) const
 Project the vector v from the viewport frame into the current frame. More...
 
bool unProject (double x, double y, Vec3d &v) const
 
bool projectLineCheck (const Vec3d &v1, Vec3d &win1, const Vec3d &v2, Vec3d &win2) const
 Project the vectors v1 and v2 from the current frame into the viewport. More...
 
QByteArray getProjectShader () const
 
void setProjectUniforms (QOpenGLShaderProgram &program) const
 
QByteArray getUnProjectShader () const
 
void setUnProjectUniforms (QOpenGLShaderProgram &program) const
 
ModelViewTranformP getModelViewTransform () const
 Get the current model view matrix.
 
Mat4f getProjectionMatrix () const
 Get the current projection matrix.
 
StelProjectorMaskType getMaskType (void) const
 Get the current type of the mask if any.
 
bool isSameProjection (const StelProjector &other) const
 Check whether the projection represented by other is the same as this. More...
 

Static Public Member Functions

static const QString maskTypeToString (StelProjectorMaskType type)
 Get a string description of a StelProjectorMaskType.
 
static StelProjectorMaskType stringToMaskType (const QString &s)
 Get a StelProjectorMaskType from a string description.
 

Protected Member Functions

 StelProjector (ModelViewTranformP amodelViewTransform)
 Private constructor. Only StelCore can create instances of StelProjector.
 
virtual bool hasDiscontinuity () const
 Return whether the projection presents discontinuities. Used for optimization.
 
virtual bool intersectViewportDiscontinuityInternal (const Vec3d &p1, const Vec3d &p2) const
 Determine whether a great circle connection p1 and p2 intersects with a projection discontinuity. More...
 
virtual bool intersectViewportDiscontinuityInternal (const Vec3d &capN, double capD) const
 Determine whether a cap intersects with a projection discontinuity.
 
virtual void computeBoundingCap ()
 Initialize the bounding cap.
 

Protected Attributes

ModelViewTranformP modelViewTransform
 
float flipHorz
 
float flipVert
 
float pixelPerRad
 
StelProjectorMaskType maskType
 
double zNear
 
double oneOverZNearMinusZFar
 
Vec4i viewportXywh
 
Vector2< qreal > viewportCenter
 
Vector2< qreal > viewportCenterOffset
 
qreal viewportFovDiameter
 
bool gravityLabels
 
float defaultAngleForGravityText
 
SphericalCap boundingCap
 
qreal devicePixelsPerPixel
 
qreal widthStretch
 

Friends

class StelPainter
 
class StelCore
 

Detailed Description

Provide the main interface to all operations of projecting coordinates from sky to screen.

The StelProjector also defines the viewport size and position. All positions in pixels are in real device pixels, which is not the same as device independent pixels. On a mac with retina screen, there are 2 device pixels per pixels. All methods from this class are threadsafe. The usual usage is to create local instances of StelProjectorP using the getProjection() method from StelCore where needed. For performing drawing using a particular projection, refer to the StelPainter class.

See also
StelProjectorP

Member Enumeration Documentation

◆ StelProjectorMaskType

Define viewport mask types.

Enumerator
MaskNone 

Regular - no mask.

MaskDisk 

For disk viewport mode (circular mask to seem like bins/telescope)

Member Function Documentation

◆ checkInViewport() [1/2]

bool StelProjector::checkInViewport ( const Vec3d pos) const

Check to see if a 2d position is inside the viewport.

TODO Optimize by storing viewportXywh[1] + viewportXywh[3] and viewportXywh[0] + viewportXywh[2] already computed

◆ checkInViewport() [2/2]

bool StelProjector::checkInViewport ( const Vec3f pos) const

Check to see if a 2d position is inside the viewport.

TODO Optimize by storing viewportXywh[1] + viewportXywh[3] and viewportXywh[0] + viewportXywh[2] already computed

◆ forward()

virtual bool StelProjector::forward ( Vec3f v) const
pure virtual

Apply the transformation in the forward direction in place.

After transformation v[2] will always contain the length of the original v: sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]) regardless of the projection type. This makes it possible to implement depth buffer testing in a way independent of the projection type. I would like to return the squared length instead of the length because of performance reasons. But then far away objects are not textured any more, perhaps because of a depth buffer overflow although the depth test is disabled?

Implemented in StelProjector2d, StelProjectorMiller, StelProjectorSinusoidal, StelProjectorOrthographic, StelProjectorMercator, StelProjectorCylinder, StelProjectorHammer, StelProjectorFisheye, StelProjectorStereographic, StelProjectorEqualArea, and StelProjectorPerspective.

◆ getViewportConvexPolygon()

SphericalRegionP StelProjector::getViewportConvexPolygon ( float  marginX = 0.,
float  marginY = 0. 
) const

Return a convex polygon on the sphere which includes the viewport in the current frame.

Parameters
marginXan extra margin in pixel which extends the polygon size in the X direction.
marginYan extra margin in pixel which extends the polygon size in the Y direction.
Returns
a SphericalConvexPolygon or the special fullSky region if the viewport cannot be represented by a convex polygon (e.g. if aperture > 180 deg).

◆ intersectViewportDiscontinuity()

bool StelProjector::intersectViewportDiscontinuity ( const Vec3d p1,
const Vec3d p2 
) const

Determine whether a great circle connection p1 and p2 intersects with a projection discontinuity.

For many projections without discontinuity, this should return always false, but for other like cylindrical projection it will return true if the line cuts the wrap-around line (i.e. at lon=180 if the observer look at lon=0).

◆ intersectViewportDiscontinuityInternal()

virtual bool StelProjector::intersectViewportDiscontinuityInternal ( const Vec3d p1,
const Vec3d p2 
) const
inlineprotectedvirtual

Determine whether a great circle connection p1 and p2 intersects with a projection discontinuity.

For many projections without discontinuity, this should return always false, but for other like cylindrical projection it will return true if the line cuts the wrap-around line (i.e. at lon=180 if the observer look at lon=0).

Reimplemented in StelProjectorMercator, StelProjectorCylinder, StelProjectorHammer, and StelProjector2d.

◆ isSameProjection()

bool StelProjector::isSameProjection ( const StelProjector other) const

Check whether the projection represented by other is the same as this.

This check is intended to tell whether the shaders returned by #getProjectShader and #getUnProjectShader are the same for this and other. The parameters compared include projection type and whether refraction is on. Numerical

◆ project() [1/3]

bool StelProjector::project ( const Vec3d v,
Vec3d win 
) const

Project the vector v from the current frame into the viewport.

Parameters
vthe vector in the current frame.
winthe projected vector in the viewport 2D frame.
Returns
true if the projected coordinate is valid.

◆ project() [2/3]

bool StelProjector::project ( const Vec3d v,
Vec3f win 
) const

Project the vector v from the current frame into the viewport.

Parameters
vthe vector in the current frame.
winthe projected vector in the viewport 2D frame.
Returns
true if the projected coordinate is valid.

◆ project() [3/3]

bool StelProjector::project ( const Vec3f v,
Vec3f win 
) const

Project the vector v from the current frame into the viewport.

Parameters
vthe vector in the current frame.
winthe projected vector in the viewport 2D frame.
Returns
true if the projected coordinate is valid.

◆ projectCheck() [1/2]

bool StelProjector::projectCheck ( const Vec3d v,
Vec3d win 
) const

Project the vector v from the current frame into the viewport.

Parameters
vthe direction vector in the current frame. Does not need to be normalized.
winthe projected vector in the viewport 2D frame. win[0] and win[1] are in screen pixels, win[2] is unused.
Returns
true if the projected point is inside the viewport.

◆ projectCheck() [2/2]

bool StelProjector::projectCheck ( const Vec3f v,
Vec3f win 
) const

Project the vector v from the current frame into the viewport.

Parameters
vthe direction vector in the current frame. Does not need to be normalized.
winthe projected vector in the viewport 2D frame. win[0] and win[1] are in screen pixels, win[2] is unused.
Returns
true if the projected point is inside the viewport.

◆ projectInPlace() [1/2]

bool StelProjector::projectInPlace ( Vec3d vd) const

Project the vector v from the current frame into the viewport.

Parameters
vdthe vector in the current frame.
Returns
true if the projected coordinate is valid.

◆ projectInPlace() [2/2]

bool StelProjector::projectInPlace ( Vec3f v) const

Project the vector v from the current frame into the viewport.

Parameters
vthe vector in the current frame.
Returns
true if the projected coordinate is valid.

◆ projectLineCheck()

bool StelProjector::projectLineCheck ( const Vec3d v1,
Vec3d win1,
const Vec3d v2,
Vec3d win2 
) const

Project the vectors v1 and v2 from the current frame into the viewport.

Parameters
v1the first vector in the current frame.
v2the second vector in the current frame.
win1the first projected vector in the viewport 2D frame.
win2the second projected vector in the viewport 2D frame.
Returns
true if at least one of the projected vector is within the viewport.

◆ unProject()

bool StelProjector::unProject ( const Vec3d win,
Vec3d v 
) const

Project the vector v from the viewport frame into the current frame.

Parameters
winthe vector in the viewport 2D frame. win[0] and win[1] are in screen pixels, win[2] is unused.
vthe unprojected direction vector in the current frame.
Returns
true if the projected coordinate is valid.