Barebones for viewport code apart from 2.7x drawing code

A new option (set in the properties region) allows the user to pick the
"new viewport" for the rendering  (in the UI: Modern Viewport).

For now we have a semi-blank file (view3d_draw.c) that can starts to take
over the drawing pipeline.

I can't guarantee we will be able to keep both drawing systems working
through the entire 2.8 development, but it should do for now.

also, we can use branches for some of the viewport development, but it's
better to keep things in 2.8 whenever we can, so people can test it.

release/scripts/startup/bl_ui/space_view3d.py

@@ -3090,7 +3090,7 @@ class VIEW3D_PT_view3d_display(Panel):
     @classmethod
     def poll(cls, context):
         view = context.space_data
-        return (view)
+        return (view) and not view.use_modern_viewport
 
     def draw(self, context):
         layout = self.layout
@@ -3188,6 +3188,11 @@ class VIEW3D_PT_view3d_shading(Panel):
     bl_region_type = 'UI'
     bl_label = "Shading"
 
+    @classmethod
+    def poll(cls, context):
+        view = context.space_data
+        return (view) and not view.use_modern_viewport
+
     def draw(self, context):
         layout = self.layout
 
@@ -3629,6 +3634,31 @@ class VIEW3D_PT_context_properties(Panel):
             rna_prop_ui.draw(self.layout, context, member, object, False)
 
 
+class VIEW3D_PT_viewport_debug(Panel):
+    bl_space_type = 'VIEW_3D'
+    bl_region_type = 'UI'
+    bl_label = "..."
+    bl_options = {'DEFAULT_CLOSED'}
+
+    @classmethod
+    def poll(cls, context):
+        view = context.space_data
+        return (view)
+
+    def draw_header(self, context):
+        view = context.space_data
+        self.layout.prop(view, "use_modern_viewport")
+
+    def draw(self, context):
+        layout = self.layout
+        view = context.space_data
+
+        layout.active = view.use_modern_viewport
+
+        col = layout.column()
+        col.label(text="Placeholder for debugging options")
+
+
 def register():
     bpy.utils.register_module(__name__)
 

source/blender/editors/space_view3d/CMakeLists.txt

@@ -52,6 +52,7 @@ set(SRC
 	view3d_buttons.c
 	view3d_camera_control.c
 	view3d_draw.c
+	view3d_draw_legacy.c
 	view3d_edit.c
 	view3d_fly.c
 	view3d_walk.c

source/blender/editors/space_view3d/view3d_header.c

@@ -334,8 +334,10 @@ void uiTemplateHeader3D(uiLayout *layout, struct bContext *C)
 		uiItemMenuEnumO(row, C, "OBJECT_OT_mode_set", "mode", name, icon);
 	}
 
-	/* Draw type */
-	uiItemR(layout, &v3dptr, "viewport_shade", UI_ITEM_R_ICON_ONLY, "", ICON_NONE);
+	if (IS_VIEWPORT_LEGACY(v3d)) {
+		/* Draw type */
+		uiItemR(layout, &v3dptr, "viewport_shade", UI_ITEM_R_ICON_ONLY, "", ICON_NONE);
+	}
 
 	if (obedit == NULL && is_paint) {
 		if (ob->mode & OB_MODE_ALL_PAINT) {

source/blender/editors/space_view3d/view3d_intern.h

@@ -193,6 +193,9 @@ void draw_sim_debug_data(Scene *scene, View3D *v3d, ARegion *ar);
 
 /* view3d_draw.c */
 void view3d_main_region_draw(const struct bContext *C, struct ARegion *ar);
+
+/* view3d_draw_legacy.c */
+void view3d_main_region_draw_legacy(const struct bContext *C, struct ARegion *ar);
 void ED_view3d_draw_depth(Scene *scene, struct ARegion *ar, View3D *v3d, bool alphaoverride);
 void ED_view3d_draw_depth_gpencil(Scene *scene, ARegion *ar, View3D *v3d);
 void ED_view3d_after_add(ListBase *lb, Base *base, const short dflag);
@@ -314,5 +317,8 @@ extern unsigned char view3d_camera_border_hack_col[3];
 extern bool view3d_camera_border_hack_test;
 #endif
 
+/* temporary test for blender 2.8 viewport */
+#define IS_VIEWPORT_LEGACY(v3d) (v3d->flag3 & V3D_NEW_VIEWPORT) == 0
+
 #endif /* __VIEW3D_INTERN_H__ */
 

source/blender/makesdna/DNA_view3d_types.h

@@ -319,6 +319,7 @@ typedef struct View3D {
 
 /* View3d->flag3 (short) */
 #define V3D_SHOW_WORLD			(1 << 0)
+#define V3D_NEW_VIEWPORT		(1 << 1)
 
 /* View3D->around */
 enum {

source/blender/makesrna/intern/rna_space.c

@@ -2736,6 +2736,12 @@ static void rna_def_space_view3d(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Volume Alpha", "Opacity (alpha) of the cameras' frustum volume");
 	RNA_def_property_update(prop, NC_SPACE | ND_SPACE_VIEW3D, NULL);
 
+	/* *** Blender 2.8 Viewport temporary *** */
+	prop = RNA_def_property(srna, "use_modern_viewport", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "flag3", V3D_NEW_VIEWPORT);
+	RNA_def_property_ui_text(prop, "Modern Viewport", "Use modern viewport");
+	RNA_def_property_update(prop, NC_SPACE | ND_SPACE_VIEW3D, NULL);
+
 	/* *** Animated *** */
 	RNA_define_animate_sdna(true);
 	/* region */