Visualization - add elliptical gradient background style

Branch [archived branch] has been created by Participant.

[revision removed]


Detailed log of new commits:

Author: achesnok
Date: Tue Sep 21 18:42:21 2021 +0300

    0031039: Visualization - add elliptical gradient background style
    
    Added new elliptical gradient fill method and updated vbackground command.

Please review the patch.
Tests' result: http://jenkins-test-12.nnov.opencascade.com/view/CR31039-master-achesnok/view/ALL/

-  short                                 myDrawMode;
+  mutable short                         myDrawMode;

myDrawMode should remain persistent.

+      myDrawMode = GL_TRIANGLE_FAN;

Please define array using common GL_TRIANGLE_STRIP format or indexed triangulation.
According to Vulkan specifications, this primitive type might not be supported by some implementations;
although it should be implemented by all OpenGL drivers, it doesn't worth complicating further porting:
https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/vkspec.html#drawing-triangle-fans

+      // the central vertex is colored in differen way

differen -> different.

 Aspect_GFM_CORNER1,
-Aspect_GFM_CORNER4
+Aspect_GFM_CORNER4,
+Aspect_GFM_ELLIP

Please document new value - describe appearance and in which order first/second colors are used.
It would be great documenting all other enumeration values as well in scope of this patch.

Please also rename enum values with Aspect_GradientFillMethod_ prefix and defined old values as aliases (see Graphic3d_TypeOfLightSource.hxx as example).
Enumeration values should not be truncated and named in CamelCase style (e.g. Aspect_GradientFillMethod_Elliptical).

Please also rebase patch on top of CR32579 (#0032579), which modified vbackground command implementation.

Branch [archived branch] has been created by Participant.

[revision removed]


Detailed log of new commits:

Author: achesnok
Date: Tue Sep 21 18:42:21 2021 +0300

    0031039: Visualization - add elliptical gradient background style
    
    Added new elliptical gradient fill method and updated vbackground command.
    Renamed enum values of Aspect_GradientFillMethod and defined aliases for old ones.

Branch [archived branch] has been updated forcibly by Participant.

[revision removed]

Branch [archived branch] has been updated forcibly by Participant.

[revision removed]

Artem, please switch to RESOLVED when current remarks will be processed.

While renaming Aspect_GFM values, please also update existing appearances of old names with fully-qualified ones.

Branch [archived branch] has been updated forcibly by Participant.

[revision removed]

Renamed all occurrences.

Branch [archived branch] has been updated forcibly by Author.

[revision removed]

Please raise the patch
- OCCT: branch CR31039_2.

Combination -
OCCT branch : [archived branch]
master SHA - [revision removed]
[revision removed]
Products branch : [archived branch] SHA - [revision removed]
was compiled on Linux, MacOS and Windows platforms and tested in optimize mode.

Number of compiler warnings:
No new/fixed warnings

Regressions/Differences/Improvements:
No regressions/differences

CPU differences:
Debian80-64:
OCCT
Total CPU difference: 17464.590000000462 / 17476.150000000354 [-0.07%]
Products
Total CPU difference: 11405.930000000111 / 11390.180000000097 [+0.14%]
Windows-64-VC14:
OCCT
Total CPU difference: 19332.171875 / 19335.34375 [-0.02%]
Products
Total CPU difference: 12772.859375 / 12782.828125 [-0.08%]


Image differences :
No differences that require special attention

Memory differences :
No differences that require special attention

Branch [archived branch] has been deleted by Author.

[revision removed]

Branch [archived branch] has been deleted by Author.

[revision removed]