Sculpt: Sculpt cursor UX improvements

This commit introduces the following changes:
- Invert the direction of the brush strength WM control. It was working in the opposite direction to any other control in Blender. Now dragging to the right increases the strength.
- Increase the alpha of the cursor
- Remove the font shadow of the numbers in the WM control. It was adding too much visual noise when rendered on top of the brush alpha
- Add a second circle to preview the strength in the cursor
- Increase the resolution of the cursor circles. Now they look smooth even when working with large brush sizes.
- Add a line preview to display the brush curve
- Don't offset the cursor preview when changing size and strength

Reviewed By: billreynish, brecht

Differential Revision: https://developer.blender.org/D5889

4 files changed, 92 insertions, 29 deletions

diff --git a/source/blender/blenkernel/BKE_brush.h b/source/blender/blenkernel/BKE_brush.h
index 68fd1b1398d..891247f8127 100644
--- a/source/blender/blenkernel/BKE_brush.h
+++ b/source/blender/blenkernel/BKE_brush.h
@@ -90,7 +90,9 @@ float BKE_brush_sample_masktex(const struct Scene *scene,
 unsigned int *BKE_brush_gen_texture_cache(struct Brush *br, int half_side, bool use_secondary);
 
 /* radial control */
-struct ImBuf *BKE_brush_gen_radial_control_imbuf(struct Brush *br, bool secondary);
+struct ImBuf *BKE_brush_gen_radial_control_imbuf(struct Brush *br,
+                                                 bool secondary,
+                                                 bool display_gradient);
 
 /* unified strength size and color */
 
diff --git a/source/blender/blenkernel/intern/brush.c b/source/blender/blenkernel/intern/brush.c
index e697b548678..95d3f47c38c 100644
--- a/source/blender/blenkernel/intern/brush.c
+++ b/source/blender/blenkernel/intern/brush.c
@@ -1596,11 +1596,11 @@ unsigned int *BKE_brush_gen_texture_cache(Brush *br, int half_side, bool use_sec
 }
 
 /**** Radial Control ****/
-struct ImBuf *BKE_brush_gen_radial_control_imbuf(Brush *br, bool secondary)
+struct ImBuf *BKE_brush_gen_radial_control_imbuf(Brush *br, bool secondary, bool display_gradient)
 {
   ImBuf *im = MEM_callocN(sizeof(ImBuf), "radial control texture");
   unsigned int *texcache;
-  int side = 128;
+  int side = 512;
   int half = side / 2;
   int i, j;
 
@@ -1609,15 +1609,17 @@ struct ImBuf *BKE_brush_gen_radial_control_imbuf(Brush *br, bool secondary)
   im->rect_float = MEM_callocN(sizeof(float) * side * side, "radial control rect");
   im->x = im->y = side;
 
-  for (i = 0; i < side; i++) {
-    for (j = 0; j < side; j++) {
-      float magn = sqrtf(pow2f(i - half) + pow2f(j - half));
-      im->rect_float[i * side + j] = BKE_brush_curve_strength_clamped(br, magn, half);
+  if (display_gradient || texcache) {
+    for (i = 0; i < side; i++) {
+      for (j = 0; j < side; j++) {
+        float magn = sqrtf(pow2f(i - half) + pow2f(j - half));
+        im->rect_float[i * side + j] = BKE_brush_curve_strength_clamped(br, magn, half);
+      }
     }
   }
 
-  /* Modulate curve with texture */
   if (texcache) {
+    /* Modulate curve with texture */
     for (i = 0; i < side; i++) {
       for (j = 0; j < side; j++) {
         const int col = texcache[i * side + j];
@@ -1626,7 +1628,6 @@ struct ImBuf *BKE_brush_gen_radial_control_imbuf(Brush *br, bool secondary)
                                         3.0f / 255.0f;
       }
     }
-
     MEM_freeN(texcache);
   }
 
diff --git a/source/blender/editors/sculpt_paint/paint_cursor.c b/source/blender/editors/sculpt_paint/paint_cursor.c
index 286cf97c20e..1f706d2f169 100644
--- a/source/blender/editors/sculpt_paint/paint_cursor.c
+++ b/source/blender/editors/sculpt_paint/paint_cursor.c
@@ -1261,7 +1261,7 @@ static void paint_draw_cursor(bContext *C, int x, int y, void *UNUSED(unused))
 
   /* set various defaults */
   const float *outline_col = brush->add_col;
-  const float outline_alpha = 0.5f;
+  const float outline_alpha = 0.7f;
   float translation[2] = {x, y};
   float final_radius = (BKE_brush_size_get(scene, brush) * zoomx);
 
@@ -1434,7 +1434,11 @@ static void paint_draw_cursor(bContext *C, int x, int y, void *UNUSED(unused))
           GPU_matrix_mul(cursor_trans);
           GPU_matrix_mul(cursor_rot);
           immUniformColor3fvAlpha(outline_col, outline_alpha);
-          imm_draw_circle_wire_3d(pos, 0, 0, rds, 40);
+          GPU_line_width(2.0f);
+          imm_draw_circle_wire_3d(pos, 0, 0, rds, 80);
+          GPU_line_width(1.0f);
+          immUniformColor3fvAlpha(outline_col, outline_alpha * 0.5f);
+          imm_draw_circle_wire_3d(pos, 0, 0, rds * clamp_f(brush->alpha, 0.0f, 1.0f), 80);
           GPU_matrix_pop();
 
           /* Update and draw dynamic mesh preview lines */
@@ -1467,7 +1471,15 @@ static void paint_draw_cursor(bContext *C, int x, int y, void *UNUSED(unused))
           /* Draw default cursor when the mouse is not over the mesh or there are no supported
            * overlays active */
           GPU_line_width(1.0f);
-          imm_draw_circle_wire_3d(pos, translation[0], translation[1], final_radius, 40);
+          /* Reduce alpha to increase the contrast when the cursor is over the mesh */
+          immUniformColor3fvAlpha(outline_col, outline_alpha * 0.8);
+          imm_draw_circle_wire_3d(pos, translation[0], translation[1], final_radius, 80);
+          immUniformColor3fvAlpha(outline_col, outline_alpha * 0.35f);
+          imm_draw_circle_wire_3d(pos,
+                                  translation[0],
+                                  translation[1],
+                                  final_radius * clamp_f(brush->alpha, 0.0f, 1.0f),
+                                  80);
         }
       }
       else {
diff --git a/source/blender/windowmanager/intern/wm_operators.c b/source/blender/windowmanager/intern/wm_operators.c
index 6da9c13d1cf..285379e90c6 100644
--- a/source/blender/windowmanager/intern/wm_operators.c
+++ b/source/blender/windowmanager/intern/wm_operators.c
@@ -41,6 +41,7 @@
 #include "CLG_log.h"
 
 #include "DNA_ID.h"
+#include "DNA_brush_types.h"
 #include "DNA_object_types.h"
 #include "DNA_screen_types.h"
 #include "DNA_scene_types.h"
@@ -58,6 +59,7 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_brush.h"
+#include "BKE_colortools.h"
 #include "BKE_context.h"
 #include "BKE_global.h"
 #include "BKE_icons.h"
@@ -1862,6 +1864,7 @@ typedef struct {
   StructRNA *image_id_srna;
   float initial_value, current_value, min_value, max_value;
   int initial_mouse[2];
+  int initial_co[2];
   int slow_mouse[2];
   bool slow_mode;
   Dial *dial;
@@ -1924,6 +1927,9 @@ static void radial_control_set_initial_mouse(RadialControl *rc, const wmEvent *e
   rc->initial_mouse[0] = event->x;
   rc->initial_mouse[1] = event->y;
 
+  rc->initial_co[0] = event->x;
+  rc->initial_co[1] = event->y;
+
   switch (rc->subtype) {
     case PROP_NONE:
     case PROP_DISTANCE:
@@ -1935,7 +1941,7 @@ static void radial_control_set_initial_mouse(RadialControl *rc, const wmEvent *e
              WM_RADIAL_CONTROL_DISPLAY_MIN_SIZE;
       break;
     case PROP_FACTOR:
-      d[0] = (1 - rc->initial_value) * WM_RADIAL_CONTROL_DISPLAY_WIDTH +
+      d[0] = rc->initial_value * WM_RADIAL_CONTROL_DISPLAY_WIDTH +
              WM_RADIAL_CONTROL_DISPLAY_MIN_SIZE;
       break;
     case PROP_ANGLE:
@@ -1962,8 +1968,10 @@ static void radial_control_set_tex(RadialControl *rc)
 
   switch (RNA_type_to_ID_code(rc->image_id_ptr.type)) {
     case ID_BR:
-      if ((ibuf = BKE_brush_gen_radial_control_imbuf(rc->image_id_ptr.data,
-                                                     rc->use_secondary_tex))) {
+      if ((ibuf = BKE_brush_gen_radial_control_imbuf(
+               rc->image_id_ptr.data,
+               rc->use_secondary_tex,
+               !ELEM(rc->subtype, PROP_NONE, PROP_PIXEL, PROP_DISTANCE)))) {
         glGenTextures(1, &rc->gltex);
         glBindTexture(GL_TEXTURE_2D, rc->gltex);
         glTexImage2D(
@@ -2061,6 +2069,22 @@ static void radial_control_paint_tex(RadialControl *rc, float radius, float alph
   immUnbindProgram();
 }
 
+static void radial_control_paint_curve(uint pos, Brush *br, float radius, int line_segments)
+{
+  GPU_line_width(2.0f);
+  immUniformColor4f(0.8f, 0.8f, 0.8f, 0.85f);
+  float step = (radius * 2.0f) / (float)line_segments;
+  BKE_curvemapping_initialize(br->curve);
+  immBegin(GPU_PRIM_LINES, line_segments * 2);
+  for (int i = 0; i < line_segments; i++) {
+    float h1 = BKE_brush_curve_strength_clamped(br, fabsf((i * step) - radius), radius);
+    immVertex2f(pos, -radius + (i * step), h1 * radius);
+    float h2 = BKE_brush_curve_strength_clamped(br, fabsf(((i + 1) * step) - radius), radius);
+    immVertex2f(pos, -radius + ((i + 1) * step), h2 * radius);
+  }
+  immEnd();
+}
+
 static void radial_control_paint_cursor(bContext *UNUSED(C), int x, int y, void *customdata)
 {
   RadialControl *rc = customdata;
@@ -2094,7 +2118,7 @@ static void radial_control_paint_cursor(bContext *UNUSED(C), int x, int y, void
       alpha = 0.75;
       break;
     case PROP_FACTOR:
-      r1 = (1 - rc->current_value) * WM_RADIAL_CONTROL_DISPLAY_WIDTH +
+      r1 = rc->current_value * WM_RADIAL_CONTROL_DISPLAY_WIDTH +
            WM_RADIAL_CONTROL_DISPLAY_MIN_SIZE;
       r2 = tex_radius = WM_RADIAL_CONTROL_DISPLAY_SIZE;
       rmin = WM_RADIAL_CONTROL_DISPLAY_MIN_SIZE;
@@ -2115,9 +2139,17 @@ static void radial_control_paint_cursor(bContext *UNUSED(C), int x, int y, void
       break;
   }
 
-  /* Keep cursor in the original place */
-  x = rc->initial_mouse[0];
-  y = rc->initial_mouse[1];
+  if (rc->subtype == PROP_ANGLE) {
+    /* Use the initial mouse position to draw the rotation preview. This avoids starting the
+     * rotation in a random direction */
+    x = rc->initial_mouse[0];
+    y = rc->initial_mouse[1];
+  }
+  else {
+    /* Keep cursor in the original place */
+    x = rc->initial_co[0];
+    y = rc->initial_co[1];
+  }
   GPU_matrix_translate_2f((float)x, (float)y);
 
   GPU_blend(true);
@@ -2141,7 +2173,6 @@ static void radial_control_paint_cursor(bContext *UNUSED(C), int x, int y, void
   uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
   immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
-  immUniformColor3fvAlpha(col, 0.5f);
 
   if (rc->subtype == PROP_ANGLE) {
     GPU_matrix_push();
@@ -2164,25 +2195,40 @@ static void radial_control_paint_cursor(bContext *UNUSED(C), int x, int y, void
   }
 
   /* draw circles on top */
-  imm_draw_circle_wire_2d(pos, 0.0f, 0.0f, r1, 40);
-  imm_draw_circle_wire_2d(pos, 0.0f, 0.0f, r2, 40);
+  GPU_line_width(2.0f);
+  immUniformColor3fvAlpha(col, 0.8f);
+  imm_draw_circle_wire_2d(pos, 0.0f, 0.0f, r1, 80);
+
+  GPU_line_width(1.0f);
+  immUniformColor3fvAlpha(col, 0.5f);
+  imm_draw_circle_wire_2d(pos, 0.0f, 0.0f, r2, 80);
   if (rmin > 0.0f) {
-    imm_draw_circle_wire_2d(pos, 0.0, 0.0f, rmin, 40);
+    /* Inner fill circle to increase the contrast of the value */
+    float black[3] = {0.0f};
+    immUniformColor3fvAlpha(black, 0.2f);
+    imm_draw_circle_fill_2d(pos, 0.0, 0.0f, rmin, 80);
+
+    immUniformColor3fvAlpha(col, 0.5f);
+    imm_draw_circle_wire_2d(pos, 0.0, 0.0f, rmin, 80);
   }
+
+  /* draw curve falloff preview */
+  if (RNA_type_to_ID_code(rc->image_id_ptr.type) == ID_BR && rc->subtype == PROP_FACTOR) {
+    Brush *br = rc->image_id_ptr.data;
+    if (br) {
+      radial_control_paint_curve(pos, br, r2, 120);
+    }
+  }
+
   immUnbindProgram();
 
-  BLF_size(fontid, 1.5 * fstyle_points * U.pixelsize, U.dpi);
-  BLF_enable(fontid, BLF_SHADOW);
-  BLF_shadow(fontid, 3, (const float[4]){0.0f, 0.0f, 0.0f, 0.5f});
-  BLF_shadow_offset(fontid, 1, -1);
+  BLF_size(fontid, 1.75f * fstyle_points * U.pixelsize, U.dpi);
 
   /* draw value */
   BLF_width_and_height(fontid, str, strdrawlen, &strwidth, &strheight);
   BLF_position(fontid, -0.5f * strwidth, -0.5f * strheight, 0.0f);
   BLF_draw(fontid, str, strdrawlen);
 
-  BLF_disable(fontid, BLF_SHADOW);
-
   GPU_blend(false);
   GPU_line_smooth(false);
 }
@@ -2633,6 +2679,8 @@ static int radial_control_modal(bContext *C, wmOperator *op, const wmEvent *even
               if (snap) {
                 new_value = ((int)ceil(new_value * 10.f) * 10.0f) / 100.f;
               }
+              /* Invert new value to increase the factor moving the mouse to the right */
+              new_value = 1 - new_value;
               break;
             case PROP_ANGLE:
               new_value = atan2f(delta[1], delta[0]) + (float)M_PI + angle_precision;