Add Fl_Gl_Window 32 bit depth buffer option.

FL/Enumerations.H

@@ -1226,7 +1226,8 @@ enum Fl_Mode {
   FL_MULTISAMPLE= 128,
   FL_STEREO     = 256,
   FL_FAKE_SINGLE = 512, // Fake single buffered windows using double-buffer
-  FL_OPENGL3    = 1024
+  FL_OPENGL3    = 1024,
+  FL_DEPTH32    = 2048,
 };
 
 // image alpha blending

FL/Fl_Gl_Window.H

@@ -150,7 +150,8 @@ public:
    - \c FL_DOUBLE - double buffered
    - \c FL_ACCUM - accumulation buffer
    - \c FL_ALPHA - alpha channel in color
-   - \c FL_DEPTH - depth buffer
+   - \c FL_DEPTH - any depth buffer (or set FL_DEPTH32 for at least 32 bits)
+   - \c FL_DEPTH32 - depth buffer with at least 32 bits
    - \c FL_STENCIL - stencil buffer
    - \c FL_MULTISAMPLE - multisample antialiasing
    - \c FL_OPENGL3 - use OpenGL version 3.0 or more.

src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.mm

@@ -94,7 +94,11 @@ static NSOpenGLPixelFormat* mode_to_NSOpenGLPixelFormat(int m, const int *alistp
       //list[n++] = AGL_DOUBLEBUFFER;
       attribs[n++] = NSOpenGLPFADoubleBuffer;
     }
-    if (m & FL_DEPTH) {
+    if (m & FL_DEPTH32) {
+      //list[n++] = AGL_DEPTH_SIZE; list[n++] = 32;
+      attribs[n++] = NSOpenGLPFADepthSize;
+      attribs[n++] = (NSOpenGLPixelFormatAttribute)32;
+    } else if (m & FL_DEPTH) {
       //list[n++] = AGL_DEPTH_SIZE; list[n++] = 24;
       attribs[n++] = NSOpenGLPFADepthSize;
       attribs[n++] = (NSOpenGLPixelFormatAttribute)24;

src/drivers/Wayland/Fl_Wayland_Gl_Window_Driver.cxx

@@ -131,7 +131,11 @@ Fl_Gl_Choice *Fl_Wayland_Gl_Window_Driver::find(int m, const int *alistp)
     EGL_NONE
   };
 
-  if (m & FL_DEPTH) config_attribs[11] = 1;
+  if (m & FL_DEPTH32)
+    config_attribs[11] = 32; // request at least 32 bits
+  else if (m & FL_DEPTH)
+    config_attribs[11] = 1; // accept any size
+
   if (m & FL_MULTISAMPLE) config_attribs[13] = 1;
   if (m & FL_STENCIL) config_attribs[15] = 1;
   if (m & FL_ALPHA) config_attribs[17] = (m & FL_RGB8) ? 8 : 1;

src/drivers/WinAPI/Fl_WinAPI_Gl_Window_Driver.cxx

@@ -79,7 +79,10 @@ Fl_Gl_Choice *Fl_WinAPI_Gl_Window_Driver::find(int m, const int *alistp)
     if ((m & FL_ACCUM) && !pfd.cAccumBits) continue;
     if ((!(m & FL_DOUBLE)) != (!(pfd.dwFlags & PFD_DOUBLEBUFFER))) continue;
     if ((!(m & FL_STEREO)) != (!(pfd.dwFlags & PFD_STEREO))) continue;
+    // Skipt his descriptor if we want a depth buffer, but this one has none
     if ((m & FL_DEPTH) && !pfd.cDepthBits) continue;
+    // Skipt his descriptor if we want a 32 bit depth buffer, but this one has less or none
+    if ((m & FL_DEPTH32) && pfd.cDepthBits < 32) continue;
     if ((m & FL_STENCIL) && !pfd.cStencilBits) continue;
 
 #if DEBUG_PFD

src/drivers/X11/Fl_X11_Gl_Window_Driver.cxx

@@ -151,7 +151,9 @@ Fl_Gl_Choice *Fl_X11_Gl_Window_Driver::find(int m, const int *alistp)
     if (m & FL_DOUBLE) {
       list[n++] = GLX_DOUBLEBUFFER;
     }
-    if (m & FL_DEPTH) {
+    if (m & FL_DEPTH32) {
+      list[n++] = GLX_DEPTH_SIZE; list[n++] = 32;
+    } else if (m & FL_DEPTH) {
       list[n++] = GLX_DEPTH_SIZE; list[n++] = 1;
     }
     if (m & FL_STENCIL) {