Theme: Radial gradient background and enum for gradient type

This commit replaces the "Use Gradient" checkbox theme option with an
enum and implements a radial background.

Whith this change, it should be easier to implemet other types of more
complex background types, like a world space oriented gradient.

Reviewed By: billreynish, fclem, brecht

Differential Revision: https://developer.blender.org/D6825

source/blender/draw/engines/overlay/overlay_background.c

@@ -30,6 +30,7 @@
 #define BG_SOLID 0
 #define BG_GRADIENT 1
 #define BG_CHECKER 2
+#define BG_RADIAL 3
 
 void OVERLAY_background_cache_init(OVERLAY_Data *vedata)
 {
@@ -67,11 +68,18 @@ void OVERLAY_background_cache_init(OVERLAY_Data *vedata)
       copy_v3_v3(color_override, v3d->shading.background_color);
       color_override[3] = 1.0f;
     }
-    else if (UI_GetThemeValue(TH_SHOW_BACK_GRAD)) {
-      background_type = BG_GRADIENT;
-    }
     else {
-      background_type = BG_SOLID;
+      switch (UI_GetThemeValue(TH_BACKGROUND_TYPE)) {
+        case TH_BACKGROUND_SINGLE_COLOR:
+          background_type = BG_SOLID;
+          break;
+        case TH_BACKGROUND_GRADIENT_LINEAR:
+          background_type = BG_GRADIENT;
+          break;
+        case TH_BACKGROUND_GRADIENT_RADIAL:
+          background_type = BG_RADIAL;
+          break;
+      }
     }
 
     DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_BACKGROUND;

source/blender/draw/engines/overlay/shaders/background_frag.glsl

@@ -12,6 +12,8 @@ out vec4 fragColor;
 #define BG_SOLID 0
 #define BG_GRADIENT 1
 #define BG_CHECKER 2
+#define BG_RADIAL 3
+#define SQRT2 1.4142135623730950488
 
 /* 4x4 bayer matrix prepared for 8bit UNORM precision error. */
 #define P(x) (((x + 0.5) * (1.0 / 16.0) - 0.5) * (1.0 / 255.0))
@@ -38,6 +40,8 @@ void main()
   float depth = texture(depthBuffer, uvcoordsvar.st).r;
 
   vec3 bg_col;
+  vec3 col_high;
+  vec3 col_low;
 
   switch (bgType) {
     case BG_SOLID:
@@ -45,9 +49,22 @@ void main()
       break;
     case BG_GRADIENT:
       /* XXX do interpolation in a non-linear space to have a better visual result. */
-      vec3 col_high = pow(colorBackground.rgb, vec3(1.0 / 2.2));
-      vec3 col_low = pow(colorBackgroundGradient.rgb, vec3(1.0 / 2.2));
+      col_high = pow(colorBackground.rgb, vec3(1.0 / 2.2));
+      col_low = pow(colorBackgroundGradient.rgb, vec3(1.0 / 2.2));
       bg_col = mix(col_low, col_high, uvcoordsvar.t);
+      /* Convert back to linear. */
+      bg_col = pow(bg_col, vec3(2.2));
+      /*  Dither to hide low precision buffer. (Could be improved) */
+      bg_col += dither();
+      break;
+    case BG_RADIAL:
+      /* Do interpolation in a non-linear space to have a better visual result. */
+      col_high = pow(colorBackground.rgb, vec3(1.0 / 2.2));
+      col_low = pow(colorBackgroundGradient.rgb, vec3(1.0 / 2.2));
+
+      vec2 uv_n = uvcoordsvar.xy - 0.5;
+      bg_col = mix(col_high, col_low, length(uv_n) * SQRT2);
+
       /* Convert back to linear. */
       bg_col = pow(bg_col, vec3(2.2));
       /*  Dither to hide low precision buffer. (Could be improved) */

source/blender/editors/include/UI_resources.h

@@ -309,7 +309,7 @@ typedef enum ThemeColorID {
   TH_GIZMO_A,
   TH_GIZMO_B,
 
-  TH_SHOW_BACK_GRAD,
+  TH_BACKGROUND_TYPE,
 
   TH_INFO_SELECTED,
   TH_INFO_SELECTED_TEXT,

source/blender/editors/interface/resources.c

@@ -196,9 +196,9 @@ const uchar *UI_ThemeGetColorPtr(bTheme *btheme, int spacetype, int colorid)
           cp = ts->back_grad;
           break;
 
-        case TH_SHOW_BACK_GRAD:
+        case TH_BACKGROUND_TYPE:
           cp = &setting;
-          setting = ts->show_back_grad;
+          setting = ts->background_type;
           break;
         case TH_TEXT:
           if (theme_regionid == RGN_TYPE_WINDOW) {

source/blender/makesdna/DNA_userdef_types.h

@@ -214,7 +214,7 @@ typedef struct ThemeSpace {
   unsigned char back[4];
   unsigned char back_grad[4];
 
-  char show_back_grad;
+  char background_type;
   char _pad0[3];
 
   /** Panel title. */
@@ -424,6 +424,14 @@ typedef struct ThemeSpace {
 
 } ThemeSpace;
 
+/* Viewport Background Gradient Types. */
+
+typedef enum eBackgroundGradientTypes {
+  TH_BACKGROUND_SINGLE_COLOR = 0,
+  TH_BACKGROUND_GRADIENT_LINEAR = 1,
+  TH_BACKGROUND_GRADIENT_RADIAL = 2,
+} eBackgroundGradientTypes;
+
 /* set of colors for use as a custom color set for Objects/Bones wire drawing */
 typedef struct ThemeWireColor {
   unsigned char solid[4];

source/blender/makesdna/intern/dna_rename_defs.h

@@ -109,3 +109,4 @@ DNA_STRUCT_RENAME_ELEM(bTheme, tstatusbar, space_statusbar)
 DNA_STRUCT_RENAME_ELEM(bTheme, ttopbar, space_topbar)
 DNA_STRUCT_RENAME_ELEM(bTheme, tuserpref, space_preferences)
 DNA_STRUCT_RENAME_ELEM(bTheme, tv3d, space_view3d)
+DNA_STRUCT_RENAME_ELEM(ThemeSpace, show_back_grad, background_type)

source/blender/makesrna/intern/rna_userdef.c

@@ -1306,6 +1306,25 @@ static void rna_def_userdef_theme_ui_panel(BlenderRNA *brna)
   RNA_def_property_update(prop, 0, "rna_userdef_theme_update");
 }
 
+const EnumPropertyItem rna_enum_userdef_theme_background_types_items[] = {
+    {TH_BACKGROUND_SINGLE_COLOR,
+     "Single Color",
+     0,
+     "Single Color",
+     "Use a solid color as viewport background"},
+    {TH_BACKGROUND_GRADIENT_LINEAR,
+     "LINEAR",
+     0,
+     "Linear Gradient",
+     "Use a screen space vertical linear gradient as viewport background"},
+    {TH_BACKGROUND_GRADIENT_RADIAL,
+     "RADIAL",
+     0,
+     "Vignette",
+     "Use a radial gradient as viewport background"},
+    {0, NULL, 0, NULL, NULL},
+};
+
 static void rna_def_userdef_theme_ui_gradient(BlenderRNA *brna)
 {
   /* Fake struct, keep this for compatible theme presets. */
@@ -1318,10 +1337,10 @@ static void rna_def_userdef_theme_ui_gradient(BlenderRNA *brna)
   RNA_def_struct_ui_text(
       srna, "Theme Background Color", "Theme settings for background colors and gradient");
 
-  prop = RNA_def_property(srna, "show_grad", PROP_BOOLEAN, PROP_NONE);
-  RNA_def_property_boolean_sdna(prop, NULL, "show_back_grad", 1);
-  RNA_def_property_ui_text(
-      prop, "Use Gradient", "Do a gradient for the background of the viewport working area");
+  prop = RNA_def_property(srna, "background_type", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_sdna(prop, NULL, "background_type");
+  RNA_def_property_enum_items(prop, rna_enum_userdef_theme_background_types_items);
+  RNA_def_property_ui_text(prop, "Background Type", "Type of background in the 3D viewport");
   RNA_def_property_update(prop, 0, "rna_userdef_theme_update");
 
   prop = RNA_def_property(srna, "high_gradient", PROP_FLOAT, PROP_COLOR_GAMMA);