Fix T43111: Node Editor (Slider) Draw Glitch

* don't allow Node Editor input max value to be less then min value
* avoid the num slider drawing glitch if softmin equals softmax
* assert if softmax/hardmax is smaller than softmin/hardmin

With this, we sort of allow softmin/hardmin and softmax/hardmax being the same.

2 files changed, 8 insertions, 2 deletions

diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index 38e331e6a1e..e730182ae37 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -2603,6 +2603,10 @@ void ui_but_update(uiBut *but)
 		}
 	}
 
+	/* max must never be smaller than min! Both being equal is allowed though */
+	BLI_assert(but->softmin <= but->softmax &&
+	           but->hardmin <= but->hardmax);
+
 	/* test for min and max, icon sliders, etc */
 	switch (but->type) {
 		case UI_BTYPE_NUM:
diff --git a/source/blender/editors/interface/interface_widgets.c b/source/blender/editors/interface/interface_widgets.c
index 645637d5130..04a886ba2a8 100644
--- a/source/blender/editors/interface/interface_widgets.c
+++ b/source/blender/editors/interface/interface_widgets.c
@@ -2874,7 +2874,7 @@ static void widget_numslider(uiBut *but, uiWidgetColors *wcol, rcti *rect, int s
 	uiWidgetBase wtb, wtb1;
 	rcti rect1;
 	double value;
-	float offs, toffs, fac;
+	float offs, toffs, fac = 0;
 	char outline[3];
 
 	widget_init(&wtb);
@@ -2905,7 +2905,9 @@ static void widget_numslider(uiBut *but, uiWidgetColors *wcol, rcti *rect, int s
 		rect1 = *rect;
 		
 		value = ui_but_value_get(but);
-		fac = ((float)value - but->softmin) * (BLI_rcti_size_x(&rect1) - offs) / (but->softmax - but->softmin);
+		if ((but->softmax - but->softmin) > 0) {
+			fac = ((float)value - but->softmin) * (BLI_rcti_size_x(&rect1) - offs) / (but->softmax - but->softmin);
+		}
 		
 		/* left part of slider, always rounded */
 		rect1.xmax = rect1.xmin + ceil(offs + U.pixelsize);