GPU: don't use multisample for entire window, only for offscreen 3D viewport.

Now that the new 3D viewport draws to a multisample offscreen buffer, there is
no good reason anymore to create an entire multisample window and pay the
performance/memory cost for other regions that don't need it.

GL_MULTISAMPLE now only gets enabled for offscreen buffers, so we don't need
to check for it throughout the UI code anymore.

Differential Revision: https://developer.blender.org/D3062

source/blender/blenloader/intern/readfile.c

@@ -6515,7 +6515,6 @@ static void direct_link_windowmanager(FileData *fd, wmWindowManager *wm)
 		win->modalcursor  = 0;
 		win->grabcursor   = 0;
 		win->addmousemove = true;
-		win->multisamples = 0;
 		win->stereo3d_format = newdataadr(fd, win->stereo3d_format);
 
 		/* multiview always fallback to anaglyph at file opening

source/blender/editors/interface/interface.c

@@ -1393,7 +1393,6 @@ void UI_block_draw(const bContext *C, uiBlock *block)
 	ARegion *ar;
 	uiBut *but;
 	rcti rect;
-	int multisample_enabled;
 	
 	/* get menu region or area region */
 	ar = CTX_wm_menu(C);
@@ -1403,11 +1402,6 @@ void UI_block_draw(const bContext *C, uiBlock *block)
 	if (!block->endblock)
 		UI_block_end(C, block);
 
-	/* disable AA, makes widgets too blurry */
-	multisample_enabled = glIsEnabled(GL_MULTISAMPLE);
-	if (multisample_enabled)
-		glDisable(GL_MULTISAMPLE);
-
 	/* we set this only once */
 	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 	
@@ -1451,9 +1445,6 @@ void UI_block_draw(const bContext *C, uiBlock *block)
 	gpuPopProjectionMatrix();
 	gpuPopMatrix();
 
-	if (multisample_enabled)
-		glEnable(GL_MULTISAMPLE);
-	
 	ui_draw_links(block);
 }
 

source/blender/editors/interface/interface_region_tooltip.c

@@ -175,12 +175,7 @@ static void ui_tooltip_region_draw_cb(const bContext *UNUSED(C), ARegion *ar)
 
 	float background_color[3];
 	float tone_bg;
-	int i, multisample_enabled;
-
-	/* disable AA, makes widgets too blurry */
-	multisample_enabled = glIsEnabled(GL_MULTISAMPLE);
-	if (multisample_enabled)
-		glDisable(GL_MULTISAMPLE);
+	int i;
 
 	wmOrtho2_region_pixelspace(ar);
 
@@ -285,9 +280,6 @@ static void ui_tooltip_region_draw_cb(const bContext *UNUSED(C), ARegion *ar)
 
 	BLF_disable(data->fstyle.uifont_id, BLF_WORD_WRAP);
 	BLF_disable(blf_mono_font, BLF_WORD_WRAP);
-
-	if (multisample_enabled)
-		glEnable(GL_MULTISAMPLE);
 }
 
 static void ui_tooltip_region_free_cb(ARegion *ar)

source/blender/editors/space_view3d/view3d_draw_legacy.c

@@ -213,11 +213,10 @@ static void draw_view_icon(RegionView3D *rv3d, rcti *rect)
 
 static void backdrawview3d(
         const struct EvaluationContext *eval_ctx, Scene *scene, ViewLayer *view_layer,
-        wmWindow *win, ARegion *ar, View3D *v3d)
+        ARegion *ar, View3D *v3d)
 {
 	RegionView3D *rv3d = ar->regiondata;
 	struct Base *base = view_layer->basact;
-	int multisample_enabled;
 
 	BLI_assert(ar->regiontype == RGN_TYPE_WINDOW);
 
@@ -264,14 +263,13 @@ static void backdrawview3d(
 	/* dithering and AA break color coding, so disable */
 	glDisable(GL_DITHER);
 
-	multisample_enabled = glIsEnabled(GL_MULTISAMPLE);
-	if (multisample_enabled)
-		glDisable(GL_MULTISAMPLE);
-
-	if (win->multisamples != USER_MULTISAMPLE_NONE) {
+	if (false) {
 		/* for multisample we use an offscreen FBO. multisample drawing can fail
 		 * with color coded selection drawing, and reading back depths from such
-		 * a buffer can also cause a few seconds freeze on OS X / NVidia. */
+		 * a buffer can also cause a few seconds freeze on OS X / NVidia.
+		 *
+		 * NOTE: code is no longer used now, but offscreen drawing is likely
+		 * what we will always want to do for the new viewport. */
 		int w = BLI_rcti_size_x(&ar->winrct);
 		int h = BLI_rcti_size_y(&ar->winrct);
 		char error[256];
@@ -327,8 +325,6 @@ static void backdrawview3d(
 	v3d->zbuf = false;
 	glDisable(GL_DEPTH_TEST);
 	glEnable(GL_DITHER);
-	if (multisample_enabled)
-		glEnable(GL_MULTISAMPLE);
 
 	if (rv3d->rflag & RV3D_CLIPPING)
 		ED_view3d_clipping_disable();
@@ -358,7 +354,7 @@ static void view3d_opengl_read_Z_pixels(ARegion *ar, int x, int y, int w, int h,
 void ED_view3d_backbuf_validate(const struct EvaluationContext *eval_ctx, ViewContext *vc)
 {
 	if (vc->v3d->flag & V3D_INVALID_BACKBUF) {
-		backdrawview3d(eval_ctx, vc->scene, vc->view_layer, vc->win, vc->ar, vc->v3d);
+		backdrawview3d(eval_ctx, vc->scene, vc->view_layer, vc->ar, vc->v3d);
 	}
 }
 
@@ -2007,11 +2003,6 @@ static void view3d_main_region_draw_objects(
 		do_compositing = GPU_fx_compositor_initialize_passes(rv3d->compositor, &ar->winrct, &ar->drawrct, &fx_settings);
 	}
 	
-	/* enables anti-aliasing for 3D view drawing */
-	if (win->multisamples != USER_MULTISAMPLE_NONE) {
-		glEnable(GL_MULTISAMPLE);
-	}
-
 	/* main drawing call */
 	view3d_draw_objects(C, &eval_ctx, scene, v3d, ar, grid_unit, true, false, do_compositing ? rv3d->compositor : NULL);
 
@@ -2020,11 +2011,6 @@ static void view3d_main_region_draw_objects(
 		GPU_fx_do_composite_pass(rv3d->compositor, rv3d->winmat, rv3d->is_persp, scene, NULL);
 	}
 
-	/* Disable back anti-aliasing */
-	if (win->multisamples != USER_MULTISAMPLE_NONE) {
-		glDisable(GL_MULTISAMPLE);
-	}
-
 	if (v3d->lay_used != lay_used) { /* happens when loading old files or loading with UI load */
 		/* find header and force tag redraw */
 		ScrArea *sa = CTX_wm_area(C);

source/blender/gpu/intern/gpu_draw.c

@@ -2095,7 +2095,7 @@ int GPU_scene_object_lights(ViewLayer *view_layer, float viewmat[4][4], int orth
 	return count;
 }
 
-static void gpu_multisample(bool enable)
+static void gpu_disable_multisample()
 {
 #ifdef __linux__
 	/* changing multisample from the default (enabled) causes problems on some
@@ -2111,16 +2111,10 @@ static void gpu_multisample(bool enable)
 	}
 
 	if (toggle_ok) {
-		if (enable)
-			glEnable(GL_MULTISAMPLE);
-		else
-			glDisable(GL_MULTISAMPLE);
+		glDisable(GL_MULTISAMPLE);
 	}
 #else
-	if (enable)
-		glEnable(GL_MULTISAMPLE);
-	else
-		glDisable(GL_MULTISAMPLE);
+	glDisable(GL_MULTISAMPLE);
 #endif
 }
 
@@ -2152,7 +2146,7 @@ void GPU_state_init(void)
 	glCullFace(GL_BACK);
 	glDisable(GL_CULL_FACE);
 
-	gpu_multisample(false);
+	gpu_disable_multisample();
 }
 
 void GPU_enable_program_point_size(void)

source/blender/makesdna/DNA_windowmanager_types.h

@@ -197,8 +197,7 @@ typedef struct wmWindow {
 	short modalcursor;  /* the current modal cursor */
 	short grabcursor;           /* cursor grab mode */
 	short addmousemove; /* internal: tag this for extra mousemove event, makes cursors/buttons active on UI switching */
-	short multisamples; /* amount of samples for OpenGL FSA the ghost window was created with, if zero no FSA */
-	short pad[3];
+	short pad[4];
 
 	int winid;                  /* winid also in screens, is for retrieving this window after read */
 

source/blender/windowmanager/intern/wm_files.c

@@ -182,7 +182,6 @@ static void wm_window_match_init(bContext *C, ListBase *wmlist)
 static void wm_window_substitute_old(wmWindowManager *wm, wmWindow *oldwin, wmWindow *win)
 {
 	win->ghostwin = oldwin->ghostwin;
-	win->multisamples = oldwin->multisamples;
 	win->active = oldwin->active;
 	if (win->active)
 		wm->winactive = win;
@@ -191,7 +190,6 @@ static void wm_window_substitute_old(wmWindowManager *wm, wmWindow *oldwin, wmWi
 		GHOST_SetWindowUserData(win->ghostwin, win);    /* pointer back */
 
 	oldwin->ghostwin = NULL;
-	oldwin->multisamples = 0;
 
 	win->eventstate = oldwin->eventstate;
 	oldwin->eventstate = NULL;

source/blender/windowmanager/intern/wm_window.c

@@ -175,7 +175,6 @@ static void wm_ghostwindow_destroy(wmWindow *win)
 	if (win->ghostwin) {
 		GHOST_DisposeWindow(g_system, win->ghostwin);
 		win->ghostwin = NULL;
-		win->multisamples = 0;
 	}
 }
 
@@ -461,16 +460,8 @@ static void wm_window_ghostwindow_add(wmWindowManager *wm, const char *title, wm
 {
 	GHOST_WindowHandle ghostwin;
 	GHOST_GLSettings glSettings = {0};
-	static int multisamples = -1;
 	int scr_w, scr_h, posy;
 	
-	/* force setting multisamples only once, it requires restart - and you cannot 
-	 * mix it, either all windows have it, or none (tested in OSX opengl) */
-	if (multisamples == -1)
-		multisamples = U.ogl_multisamples;
-
-	glSettings.numOfAASamples = multisamples;
-
 	/* a new window is created when pageflip mode is required for a window */
 	if (win->stereo3d_format->display_mode == S3D_DISPLAY_PAGEFLIP)
 		glSettings.flags |= GHOST_glStereoVisual;
@@ -508,9 +499,6 @@ static void wm_window_ghostwindow_add(wmWindowManager *wm, const char *title, wm
 		if (win->eventstate == NULL)
 			win->eventstate = MEM_callocN(sizeof(wmEvent), "window event state");
 
-		/* store multisamples window was created with, in case user prefs change */
-		win->multisamples = multisamples;
-		
 		/* store actual window size in blender window */
 		bounds = GHOST_GetClientBounds(win->ghostwin);
 

source/blender/windowmanager/manipulators/intern/wm_manipulator_map.c

@@ -390,16 +390,9 @@ static void manipulators_draw_list(const wmManipulatorMap *mmap, const bContext
 		return;
 	}
 
-	const bool draw_multisample = (U.ogl_multisamples != USER_MULTISAMPLE_NONE);
-
 	/* TODO this will need it own shader probably? don't think it can be handled from that point though. */
 /*	const bool use_lighting = (U.manipulator_flag & V3D_MANIPULATOR_SHADED) != 0; */
 
-	/* enable multisampling */
-	if (draw_multisample) {
-		glEnable(GL_MULTISAMPLE);
-	}
-
 	bool is_depth_prev = false;
 
 	/* draw_manipulators contains all visible manipulators - draw them */
@@ -435,10 +428,6 @@ static void manipulators_draw_list(const wmManipulatorMap *mmap, const bContext
 	if (is_depth_prev) {
 		glDisable(GL_DEPTH_TEST);
 	}
-
-	if (draw_multisample) {
-		glDisable(GL_MULTISAMPLE);
-	}
 }
 
 void WM_manipulatormap_draw(