arglCameraFrustum |
Create an OpenGL perspective projection matrix.
void arglCameraFrustum(
const ARParam *cparam,
const double focalmin,
const double focalmax,
GLdouble m_projection[16]);
cparam- Pointer to a set of ARToolKit camera parameters for the current video source.
focalmax- The maximum distance at which geometry will be rendered. Any geometry further away from the camera than this distance will be clipped and will not be appear in a rendered frame. Thus, this value should be set high enough to avoid clipping of any geometry you care about. However, the precision of the depth buffer is correlated with the ratio of focalmin to focalmax, thus you should not set focalmax any higher than it needs to be. This value should be specified in the same units as your OpenGL drawing.
focalmin- The minimum distance at which geometry will be rendered. Any geometry closer to the camera than this distance will be clipped and will not be appear in a rendered frame. Thus, this value should be set low enough to avoid clipping of any geometry you care about. However, the precision of the depth buffer is correlated with the ratio of focalmin to focalmax, thus you should not set focalmin any lower than it needs to be. Additionally, geometry viewed in a stereo projections that is too close to camera is difficult and tiring to view, so if you are rendering stereo perspectives you should set this value no lower than the near-point of the eyes. The near point in humans varies, but usually lies between 0.1 m 0.3 m. This value should be specified in the same units as your OpenGL drawing.
m_projection- Pointer to a array of 16 GLdoubles, which will be filled out with a projection matrix suitable for passing to OpenGL. The matrix is specified in column major order.
Use this function to create a matrix suitable for passing to OpenGL to set the viewing projection.
arglCameraFrustumRH |
(description)
void arglCameraFrustumRH(
const ARParam *cparam,
const double focalmin,
const double focalmax,
GLdouble m_projection[16]);
(name)- (description)
(description)
arglCameraView |
Create an OpenGL viewing transformation matrix.
void arglCameraView(
const double para[3][4],
GLdouble m_modelview[16],
const double scale);
para- Pointer to 3x4 matrix array of doubles which specify the position of an ARToolKit marker, as returned by arGetTransMat().
m_modelview- Pointer to a array of 16 GLdoubles, which will be filled out with a modelview matrix suitable for passing to OpenGL. The matrix is specified in column major order.
scale- Specifies a scaling between ARToolKit's units (usually millimeters) and OpenGL's coordinate system units. What you pass for the scalefactor parameter depends on what units you want to do your OpenGL drawing in. If you use a scalefactor of 1.0, then
To use different OpenGL units, e.g. metres, then you would pass 0.001.
Use this function to create a matrix suitable for passing to OpenGL to set the viewing transformation of the virtual camera.
arglCameraViewRH |
(description)
void arglCameraViewRH(
const double para[3][4],
GLdouble m_modelview[16],
const double scale);
(name)- (description)
(description)
arglCleanup |
Free memory used by gsub_lite associated with the specified context.
void arglCleanup(
ARGL_CONTEXT_SETTINGS_REF contextSettings);
contextSettings- A reference to ARGL's settings for an OpenGL context, as returned by arglSetupForCurrentContext().
Should be called after no more argl* functions are needed, in order
to prevent memory leaks etc.
The library can be setup again for the context at a later time by calling
arglSetupForCurrentContext() again.
arglDispImage |
Display an ARVideo image, by drawing it using OpenGL.
void arglDispImage(
ARUint8 *image,
const ARParam *cparam,
const double zoom,
ARGL_CONTEXT_SETTINGS_REF contextSettings);
image- Pointer to the tightly-packed image data (as returned by arVideoGetImage()). The horizontal and vertical dimensions of the image data must exactly match the values specified in the fields cparam->xsize and cparam->ysize (see below).
The first byte of image data corresponds to the first component of the top-left-most pixel in the image. The data continues with the remaining pixels of the first row, followed immediately by the pixels of the second row, and so on to the last byte of the image data, which corresponds to the last component of the bottom-right-most pixel.cparam- Pointer to a set of ARToolKit camera parameters for the current video source. The size of the source image is taken from the fields xsize and ysize of the ARParam structure pointed to. Also, when the draw mode is AR_DRAW_BY_TEXTURE_MAPPING (see the documentation for the global variable arglDrawMode) the field dist_factor of the ARParam structure pointed to will be taken as the amount to un-warp the supplied image.
zoom- The amount to scale the video image up or down. To draw the video image double size, use a zoom value of 2.0. To draw the video image half size use a zoom value of 0.5.
contextSettings- A reference to ARGL's settings for the current OpenGL context, as returned by arglSetupForCurrentContext() for this context. It is the callers responsibility to make sure that the current context at the time arglDisplayImage() is called matches that under which contextSettings was created.
This function draws an image from an ARVideo source to the current
OpenGL context. This operation is most useful in video see-through
augmented reality applications for drawing the camera view as a
background image, but can also be used in other ways.
An undistorted image is drawn with the lower-left corner of the
bottom-left-most pixel at OpenGL screen coordinates (0,0), and the
upper-right corner of the top-right-most pixel at OpenGL screen
coodinates (x * zoom, y * zoom), where x and y are the values of the
fields cparam->xsize and cparam->ysize (see below) and zoom is the
value of the parameter zoom (also see below). If cparam->dist_factor
indicates that an un-warping correction should be applied, the actual
coordinates will differ from the values specified here.
OpenGL state: Drawing is performed with depth testing and lighting
disabled, and thus leaves the the depth buffer (if any) unmodified. If
pixel transfer is by texturing (see documentation for arglDrawMode),
the drawing is done in replacement texture environment mode.
The depth test enable and lighting enable state and the texture
environment mode are restored before the function returns.
arglDispImageStateful |
Display an ARVideo image, by drawing it using OpenGL, using and modifying current OpenGL state.
void arglDispImageStateful(
ARUint8 *image,
const ARParam *cparam,
const double zoom,
ARGL_CONTEXT_SETTINGS_REF contextSettings); This function is identical to arglDispImage except that whereas
arglDispImage sets an orthographic 2D projection and the OpenGL state
prior to drawing, this function does not. It also does not restore any
changes made to OpenGL state.
This allows you to do effects with your image, other than just drawing it
2D and with the lower-left corner of the bottom-left-most pixel attached
to the bottom-left (0,0) of the window. For example, you might use a
perspective projection instead of an orthographic projection with a
glLoadIdentity() / glTranslate() on the modelview matrix to place the
lower-left corner of the bottom-left-most pixel somewhere other than 0,0
and leave depth-testing enabled.
See the documentation for arglDispImage() for more information.
arglDistortionCompensationGet |
Enquire as to the enable state of camera lens distortion compensation in arglDispImage.
int arglDistortionCompensationGet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
int *enable);
contextSettings- A reference to ARGL's settings for the current OpenGL context, as returned by arglSetupForCurrentContext() for this context.
enable- Pointer to an integer value which will be set to TRUE if distortion compensation is enabled in the specified context, or FALSE if it is disabled.
By default, arglDispImage compensates for the distortion of the camera's acquired image caused by the lens when it draws. This function enquires as to whether arglDispImage is currently doing compensation or not.
arglDistortionCompensationSet |
Set compensation for camera lens distortion in arglDispImage to off or on.
int arglDistortionCompensationSet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
int enable);
contextSettings- A reference to ARGL's settings for the current OpenGL context, as returned by arglSetupForCurrentContext() for this context.
enable- TRUE to enabled distortion compensation, FALSE to disable it. The default state for new contexts is enable = TRUE.
By default, arglDispImage compensates for the distortion of the camera's acquired image caused by the lens when it draws. By calling this function with enabled = FALSE, this compensation will be disabled in the specified drawing context. It may be re-enabled at any time. This function is useful if you need to draw an image, but do not know the extent of the camera's lens distortion (such as during distortion calibration). While distortion compensation is disabled, the dist_factor[] array in a the camera cparam structure passed to arglDispImage is ignored.
arglDrawModeGet |
Get method by which arglDispImage() is transfering pixels.
int arglDrawModeGet(
ARGL_CONTEXT_SETTINGS_REF contextSettings); Enquires as to the current method by which arglDispImage() is transferring pixels to OpenGL for display. See arglDrawModeSet() for more information.
arglDrawModeSet |
Set method by which arglDispImage() will transfer pixels.
void arglDrawModeSet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
const int mode); This setting determines the method by which arglDispImage transfers pixels
of an image to OpenGL for display. Setting this
variable to a value of AR_DRAW_BY_GL_DRAW_PIXELS specifies the use of the
OpenGL DrawPixels functions to do the transfer. Setting this variable to a value of
AR_DRAW_BY_TEXTURE_MAPPING specifies the use of OpenGL TexImage2D functions to do the
transfer. The DrawPixels method is guaranteed to be available on all
implementations, but arglDispImage does not correct the image
for camera lens distortion under this method. In contrast, TexImage2D is only
available on some implementations, but allows arglDispImage() to apply a correction
for camera lens distortion, and additionally offers greater potential for
accelerated drawing on some implementations.
The initial value is AR_DRAW_BY_TEXTURE_MAPPING.
arglPixelFormatGet |
Get the format of pixel data in which arglDispImage*() is expecting data to be passed.
int arglPixelFormatGet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
AR_PIXEL_FORMAT *format,
int *size);
contextSettings- A reference to ARGL's settings for the current OpenGL context, as returned by arglSetupForCurrentContext() for this context.
format- A symbolic constant for the pixel format in use. See AR_PIXEL_FORMAT in ar.h for a list of all possible formats.
size- The number of bytes of memory occupied per pixel, for the given format.
This function enquires as to the current format of pixel data being expected by the arglDispImage*() functions. The default format is determined by the value of AR_DEFAULT_PIXEL_FORMAT at the time the library was built.
arglPixelFormatSet |
Set the format of pixel data which will be passed to arglDispImage*()
int arglPixelFormatSet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
AR_PIXEL_FORMAT format);
contextSettings- A reference to ARGL's settings for the current OpenGL context, as returned by arglSetupForCurrentContext() for this context.
format- A symbolic constant for the pixel format being set. See AR_PIXEL_FORMAT in ar.h for a list of all possible formats.
(description) In gsub_lite, the format of the pixels (i.e. the arrangement of components within each pixel) can be changed at runtime. Use this function to inform gsub_lite the format the pixels being passed to arglDispImage*() functions are in. This setting applies only to the context passed in parameter contextSettings. The default format is determined by the value of AR_DEFAULT_PIXEL_FORMAT at the time the library was built. Usually, image data is passed in directly from images generated by ARVideo, and so you should ensure that ARVideo is generating pixels of the same format.
arglSetupForCurrentContext |
Initialise the gsub_lite library for the current OpenGL context.
ARGL_CONTEXT_SETTINGS_REF arglSetupForCurrentContext(
void); This function performs required setup of the gsub_lite library
for the current OpenGL context and must be called before any other argl*()
functions are called for this context.
An OpenGL context holds all of the state of the OpenGL machine, including
textures and display lists etc. There will usually be one OpenGL context
for each window displaying OpenGL content.
Other argl*() functions whose operation depends on OpenGL state will
require an ARGL_CONTEXT_SETTINGS_REF. This is just so that
they can keep track of per-context variables.
You should call arglCleanup() passing in the ARGL_CONTEXT_SETTINGS_REF
when you have finished with the library for this context.
arglTexmapModeGet |
Enquire whether full or half-resolution TexImage2D pixel-transfer is being used in arglDispImage().
int arglTexmapModeGet(
ARGL_CONTEXT_SETTINGS_REF contextSettings); Enquires as to the current value of the TexmapMode setting. See arglTexmapModeSet() for more info.
arglTexmapModeSet |
Determines use of full or half-resolution TexImage2D pixel-transfer in arglDispImage().
void arglTexmapModeSet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
const int mode); When arglDrawModeSet(AR_DRAW_BY_TEXTURE_MAPPING) has been called, the value of this
setting determines whether full or half-resolution data is transferred to the
texture. Calling this function with a mode value of AR_DRAW_TEXTURE_FULL_IMAGE
uses all available pixels in the source image data. A value of
AR_DRAW_TEXTURE_HALF_IMAGE discards every second row
in the source image data, defining a half-height texture which is then drawn stretched
vertically to double its height.
The latter method is well-suited to drawing interlaced images, as would be obtained
from DV camera sources in interlaced mode or composite video sources.
The initial value is AR_DRAW_TEXTURE_FULL_IMAGE.
arglTexRectangleGet |
Enquire as to use of rectangular TexImage2D pixel-transfer in arglDispImage().
int arglTexRectangleGet(
ARGL_CONTEXT_SETTINGS_REF contextSettings); Enquires as to the current value of the TexRectangle setting. See arglTexRectangleSet() for more info.
arglTexRectangleSet |
Determines use of rectangular TexImage2D pixel-transfer in arglDispImage().
void arglTexRectangleSet(
ARGL_CONTEXT_SETTINGS_REF contextSettings,
const int state); On implementations which support the OpenGL extension for rectangular textures (of
non power-of-two size), and when arglDrawMode is set to AR_DRAW_BY_TEXTURE_MAPPING,
the value of this variable determines whether rectangular textures or ordinary
(power-of-two) textures are used by arglDispImage(). A value of TRUE specifies the
use of rectangluar textures. A value of FALSE specifies the use of ordinary textures.
If the OpenGL driver available at runtime does not support for rectangular textures,
changing the value of this setting to TRUE will result calls to arglDispImage
performing no drawing.
© 2003-2006 Philip Lamb (Last Updated June 23, 2006)