class TGLUtil

 Returns a tesselator for direct drawing when using 3-vertices with
 single precision.

 Returns a tesselator for direct drawing when using 4-vertices with
 single precision.

 Returns a tesselator for direct drawing when using 3-vertices with
 double precision.

 Returns a tesselator for direct drawing when using 4-vertices with
 double precision.

 Initialize globals that require other libraries to be initialized.
 This is called from TGLWidget creation function.

static: get draw quality

static: set draw quality

static: reset draw quality

static: get default draw quality

static: set default draw quality

 Check current GL error state, outputing details via ROOT
 Error method if one

 Prevent further color changes.

 Allow color changes.

 Returns true if color lockcount is greater than 0.

 Set color from TGLColor.

 Set color from TGLColor and alpha value.

 Set color from TGLColor and alpha value.

 Set color from color_index and GL-style alpha (default 1).

 Set color from color_index and ROOT-style transparency (default 0).

 Wrapper for glColor3ub.

 Wrapper for glColor4ub.

 Wrapper for glColor3ubv.

 Wrapper for glColor4ubv.

 Wrapper for glColor3f.

 Wrapper for glColor4f.

 Wrapper for glColor3fv.

 Wrapper for glColor4fv.

 Convert from point/screen coordinates to GL viewport coordinates.

 Convert from point/screen coordinates to GL viewport coordinates.

 Returns scaling factor between screen points and GL viewport pixels.
 This is what is returned by gVirtualX->GetOpenGLScalingFactor() but is
 cached here to avoid a virtual function call as it is used quite often in
 TGLPhysical shape when drawing the selection highlight.

 Return extra scaling factor for points and lines.
 By default this is set to the same value as ScreenScalingFactor to keep
 the same appearance. To override use rootrc entry, e.g.:
 OpenGL.PointLineScalingFactor: 1.0

 Returns picking radius.

 Get global point-size scale.

 Set global point-size scale.

 Returns global line-width scale.

 Set global line-width scale.

 Set the point-size, taking the global scaling into account.
 Wrapper for glPointSize.

 Set the line-width, taking the global scaling into account.
 Wrapper for glLineWidth.

 Get the point-size, taking the global scaling into account.

 Get the line-width, taking the global scaling into account.

 Extend pick region for large point-sizes or line-widths.

 End extension of the pick region.

 Render polymarkers at points specified by p-array.
 Supports point and cross-like styles.

 Render polymarkers at points specified by p-array.
 Supports point and cross-like styles.
 Color is set externally. Lighting is disabled externally.

 Render markers as circular or square points.
 Color is never changed.

 Render markers as circular or square points.
 Color is never changed.

 Render markers as crosses.
 Color is never changed.

 Render markers as crosses.
 Color is never changed.

 Render poly-line as specified by the p-array.

 Setup drawing parrameters according to passed TAttLine.

 Restore previous line drawing state.

 Set basic draw colors from 4 component 'rgba'
 Used by other TGLUtil drawing routines

 Sets basic (unlit) color - glColor
 and also GL materials (see OpenGL docs) thus:

 diffuse  : rgba
 ambient  : 0.0 0.0 0.0 1.0
 specular : 0.6 0.6 0.6 1.0
 emission : rgba/4.0
 shininess: 60.0

 emission is set so objects with no lights (but lighting still enabled)
 are partially visible

 Draw sphere, centered on vertex 'position', with radius 'radius',
 color 'rgba'

 Draw thick line (tube) defined by 'line', with head at end shape
 'head' - box/arrow/none, (head) size 'size', color 'rgba'

 Draw thick line (tube) running from 'start', length 'vector',
 with head at end of shape 'head' - box/arrow/none,
 (head) size 'size', color 'rgba'

 Draw ring, centered on 'center', lying on plane defined by 'center' & 'normal'
 of outer radius 'radius', color 'rgba'

 Draw a sphere- marker on world-coordinate 'pos' with pixel
 radius 'radius'. Color argument is optional.

 Draw simple xyz-axes for given bounding-box.

 Draw number in string 'num' via internal 8x8-pixel bitmap on
 vertex 'pos'. If 'center' is true, the number is centered on 'pos'.
 Only numbers, '.', '-' and ' ' are supported.