OpenGL implementation of all `fl_` "Drawing Fast Shapes" graphics calls (#385)

* Fix build system for unites,

* Updated unittest to check OpenGL drawing.

Making sure that OpenGL drawing is exactly the same
as native drawing to make FLTK widget rendering
look the same in GL windows.

* Make OpenGL optional.

* Implemented clipping in OpenGL

* unites drawing fast shapes

* Fixed CMake

* Updating unittest.

Added tests for fl_pi and fl_arc (int)
Renamed tab to render complex shapes.

* Improved OpenGL FLTK drawing emulation.

* Fixed GTK ROUND DOWN BOX

* Fixing Makefile for unittest

* Correctly aligning OpenGL text.

* Fixed text alignment in GL windows.

Explained the "FLTK over GL " example in Cube.

* Overlapping test.

* Better GL graphics alignment.

* Drawing the focus rect.

* Adding Alpha Channel support for GL.

* Added FLTK-on-GL documentation.

1 files changed, 22 insertions, 8 deletions

diff --git a/src/drivers/OpenGL/Fl_OpenGL_Graphics_Driver_line_style.cxx b/src/drivers/OpenGL/Fl_OpenGL_Graphics_Driver_line_style.cxx
index 89dea699d..c1963352b 100644
--- a/src/drivers/OpenGL/Fl_OpenGL_Graphics_Driver_line_style.cxx
+++ b/src/drivers/OpenGL/Fl_OpenGL_Graphics_Driver_line_style.cxx
@@ -31,27 +31,41 @@
 // OpenGL implementation does not support cap and join types
 
 void Fl_OpenGL_Graphics_Driver::line_style(int style, int width, char* dashes) {
-
   if (width<1) width = 1;
+  line_width_ = width;
+
+  int stipple = style & 0x00ff;
+  line_stipple_ = stipple;
+//  int cap     = style & 0x0f00;
+//  int join    = style & 0xf000;
 
-  if (style==FL_SOLID) {
+  if (stipple==FL_SOLID) {
     glLineStipple(1, 0xFFFF);
     glDisable(GL_LINE_STIPPLE);
   } else {
-    switch (style) {
+    char enable = 1;
+    switch (stipple & 0x00ff) {
       case FL_DASH:
-        glLineStipple(width, 0x0F0F); // ....****....****
+        glLineStipple(pixels_per_unit_*line_width_, 0x0F0F); // ....****....****
         break;
       case FL_DOT:
-        glLineStipple(width, 0x5555); // .*.*.*.*.*.*.*.*
+        glLineStipple(pixels_per_unit_*line_width_, 0x5555); // .*.*.*.*.*.*.*.*
         break;
       case FL_DASHDOT:
-        glLineStipple(width, 0x2727); // ..*..***..*..***
+        glLineStipple(pixels_per_unit_*line_width_, 0x2727); // ..*..***..*..***
         break;
       case FL_DASHDOTDOT:
-        glLineStipple(width, 0x5757); // .*.*.***.*.*.***
+        glLineStipple(pixels_per_unit_*line_width_, 0x5757); // .*.*.***.*.*.***
         break;
+      default:
+        glLineStipple(1, 0xFFFF);
+        enable = 0;
     }
-    glEnable(GL_LINE_STIPPLE);
+    if (enable)
+      glEnable(GL_LINE_STIPPLE);
+    else
+      glDisable(GL_LINE_STIPPLE);
   }
+  glLineWidth( (GLfloat)(pixels_per_unit_ * line_width_) );
+  glPointSize( (GLfloat)(pixels_per_unit_) );
 }