Eagle Customization - opengl settings

OpenGL Configuration

This section contains configurable settings to tweak the OpenGL implementation in Eagle. These settings can be altered to match your application type, models and mode of use of OpenGL display process.

Configuration File Entries

	OPENGL
Values	yes \| unset
Description	OpenGL rendering in Eagle is enabled by using this switch When enabled OPENGL=YES allows rendering in an OpenGL window which is triggered by issuing the OPENGL command. Disable the capability by leaving the variable unset
Default	yes
Example	OPENGL=yes

	DEBUG_GL
Values	yes \| no
Description	Define if OpenGL debugging messages are displayed in the Eagle message window. NO disables messages or YES displays messages. Note that using YES also slows down OpenGL performance
Default	no
Example	DEBUG_GL=yes

	ARCS_APPROX
Values	a number
Description	Define if OpenGL debugging messages are displayed in the Eagle message window. NO disables messages or YES displays messages. Note that using YES also slows down OpenGL performance
Default	10.5
Example	ARCS_APPROX=16

	QUADRATIC_APPROX
Values	a number
Description	The approximation for quadrics, a surface defined by an algebraic equation of degree two is called a quadric. Spheres, circular cylinders, and circular cones are quadrics.
Default	16
Example	ARCS_APPROX=64

	QUADRATIC_TESSELATION
Values	1 \| 2
Description	Define the way in which quadrics are represented in OpenGL. For lines set QUADRIC_TESSELATION=1 or set to 2 for silhouette.
Default	2
Example	QUADRATIC_TESSELATION=1

	NURBS_APPROX
Values	a number
Description	The approximation settings for Nurbs ( Non-Uniform Rational B-Splines) which are mathematical representations of 3-D geometry that can accurately describe any shape from a simple 2-D line, circle, arc, or curve to the most complex 3-D organic free-form surface or solid.
Default	0.25
Example	NURBS_APPROX=0.25

	NURBS_TESSELATION
Values	PATCH \| POLYGON
Description	Define the way to represent NURBS
Default	PATCH
Example	NURBS_TESSELATION=POLYGON

	NORMALIZE
Values	a number
Description	Define the coordinates normalization factor
Default	PATCH
Example	NORMALIZE=0.001

	HALF_TONE
Values	YES \| unset
Description	A flag used to render wireframe graphics with a default material or the solid color. HALF_TONE=YES [Default material] or unset [Solid Color]
Default	YES
Example	HALF_TONE=

	DEFAULT_LIGHT
Values	D \| A \| P
Description	Set the default lighting type. The default light source is positional (P) but it is also possible to set the light source as a directional (D) or ambient (A) type. Light setting influences both performance (about 5% improvement using a directional one and 20% using the ambient one) and quality (the ambient type produces a quite flat result even thought shading model is Gouraud).
Default	P
Example	DEFAULT_LIGHT=A

	CULLING
Values	1 \| 0
Description	Enable or disable culling in OpenGL. The effect of culling means a performance gain can be achieved if culling is well implemented in the GL library in use on the system or if it is available on the graphic card. An example of setting for culling could be CULLING=0 which would account for cases when UFOs are not rendered correctly in the OpenGL window. This could happen if UFOs contain quadrilateral faces. Performance gain can be achieved if culling is well implemented.
Default	0
Example	CULLING=1

	DEPTHFIELD
Values	a number
Description	Define the point of focus such that more distant objects will be rendered with depth blurred.
Default	0
Example	DEPTHFIELD=1

	PO_FACTOR
Values	a number
Description	Used enhance OpenGL graphics when the rendering mode is HIDE or EDGES , two environment variables (PO_FACTOR and PO_UNITS) are used. They are used to slightly offset items to avoid the possibility of overlapping geometries causing pseudo-dashed lines to be displayed.
Default	1
Example	PO_FACTOR=1

	PO_FACTOR
Values	a number
Description	Used to enhance OpenGL graphics when the rendering mode is HIDE or EDGES by slightly offsetting items to avoid overlapping geometry causing pseudo-dashed lines to be displayed. The two modes: FAKE and SHADE, are now deprecated for removal and should not be used. These settings are dynamic and are re-evaluated when GLMODE changes.
Default	0
Example	PO_UNITS=0

	PO_UNITS
Values	a number
Description	Used to enhance OpenGL graphics when the rendering mode is HIDE or EDGES by slightly offsetting items to avoid overlapping geometry causing pseudo-dashed lines to be displayed. The two modes: FAKE and SHADE, are now deprecated for removal and should not be used. These settings are dynamic and are re-evaluated when GLMODE changes.
Default	0
Example	PO_UNITS=0

	POLYGON_OFFSET_DISABLED
Values	yes \| no
Description	Enable or disable offsetting on faces in OpenGL
Default	no
Example	POLYGON_OFFSET_DISABLED=yes

	ANTIALIASING
Values	yes \|no
Description	Trigger anti-aliasing to minimize the distortion artifacts
Default	no
Example	ANTIALIASING=yes

	SURFTOL
Values	a number
Description	Tolerance for surfaces where a lower the number can improve surface operations but may affect performance
Default	2.0
Example	SURFTOL=3.0

	OPENGL_SILH
Values	a number
Description	Used to dynamically draw silhouette edges for pipes and Ufos in the OpenGL window
Default	no
Example	OPENGL_SILH=yes

Additional notes for Version 14 Nurbs

The following environment variables for the OpenGL are read at each rendering:

DEBUG_GL

NORMALIZE

NURBS_APPROX

CULLING

NURBS_FACETED

NURBS_TRIMMED

NURBS_PRECISION

NURBS_BLEND_NORMALS

NURBS_UV_RECALCULATE

Please refer also to the Nurbs Configuration Settings for details on variables not listed in this topic relating to OpenGL rendering of Nurbs.