Sculpt: Multiplane Scrape Brush

The Multiplane Scrape brush creates sharp edges with a given fixed angle by trimming the mesh with two planes in local space at the same time.  When working with stylized or hard surface models, this brush produces way better results and is more predictable than any other crease/flatten brush based on curves and alphas.
It is also the first brush we have than can produce hard surface concave creases.
The Multiplane Scrape Brush also has a dynamic mode where it samples the surface to fit the angle and scrape planes during a stroke. With this mode enabled you can sculpt multiple times over the same edge without creating artifacts.
It can also create creases that change between concave and convex during the same stroke.

The behavior of this brush will improve after merging patches like D5993 and its behavior in concave creases can still be improved, so I will keep tweaking its parameters and default values once we have all brush properties available.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6174

1 files changed, 82 insertions, 0 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_cursor.c b/source/blender/editors/sculpt_paint/paint_cursor.c
index b9af33e7ad6..ac738f326a3 100644
--- a/source/blender/editors/sculpt_paint/paint_cursor.c
+++ b/source/blender/editors/sculpt_paint/paint_cursor.c
@@ -1214,6 +1214,70 @@ static void sculpt_geometry_preview_lines_draw(const uint gpuattr, SculptSession
   }
 }
 
+static void sculpt_multiplane_scrape_preview_draw(const uint gpuattr,
+                                                  SculptSession *ss,
+                                                  float *outline_col,
+                                                  float outline_alpha)
+{
+  float local_mat_inv[4][4];
+  invert_m4_m4(local_mat_inv, ss->cache->stroke_local_mat);
+  GPU_matrix_mul(local_mat_inv);
+  float angle = ss->cache->multiplane_scrape_sampled_angle;
+  if (ss->cache->pen_flip || ss->cache->invert) {
+    angle = -angle;
+  }
+
+  float offset = ss->cache->radius * 0.25f;
+
+  float p[3] = {0.0f, 0.0f, ss->cache->radius};
+  float y_axis[3] = {0.0f, 1.0f, 0.0f};
+  float p_l[3];
+  float p_r[3];
+  float area_center[3] = {0.0f, 0.0f, 0.0f};
+  rotate_v3_v3v3fl(p_r, p, y_axis, DEG2RADF((angle + 180) * 0.5f));
+  rotate_v3_v3v3fl(p_l, p, y_axis, DEG2RADF(-(angle + 180) * 0.5f));
+
+  immBegin(GPU_PRIM_LINES, 14);
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+  immVertex3f(gpuattr, p_r[0], p_r[1] + offset, p_r[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+  immVertex3f(gpuattr, p_l[0], p_l[1] + offset, p_l[2]);
+
+  immVertex3f(gpuattr, area_center[0], area_center[1] - offset, area_center[2]);
+  immVertex3f(gpuattr, p_r[0], p_r[1] - offset, p_r[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] - offset, area_center[2]);
+  immVertex3f(gpuattr, p_l[0], p_l[1] - offset, p_l[2]);
+
+  immVertex3f(gpuattr, area_center[0], area_center[1] - offset, area_center[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+
+  immVertex3f(gpuattr, p_r[0], p_r[1] - offset, p_r[2]);
+  immVertex3f(gpuattr, p_r[0], p_r[1] + offset, p_r[2]);
+
+  immVertex3f(gpuattr, p_l[0], p_l[1] - offset, p_l[2]);
+  immVertex3f(gpuattr, p_l[0], p_l[1] + offset, p_l[2]);
+
+  immEnd();
+
+  immUniformColor3fvAlpha(outline_col, outline_alpha * 0.1f);
+  immBegin(GPU_PRIM_TRIS, 12);
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+  immVertex3f(gpuattr, p_r[0], p_r[1] + offset, p_r[2]);
+  immVertex3f(gpuattr, p_r[0], p_r[1] - offset, p_r[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] - offset, area_center[2]);
+  immVertex3f(gpuattr, p_r[0], p_r[1] - offset, p_r[2]);
+
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+  immVertex3f(gpuattr, p_l[0], p_l[1] + offset, p_l[2]);
+  immVertex3f(gpuattr, p_l[0], p_l[1] - offset, p_l[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] + offset, area_center[2]);
+  immVertex3f(gpuattr, area_center[0], area_center[1] - offset, area_center[2]);
+  immVertex3f(gpuattr, p_l[0], p_l[1] - offset, p_l[2]);
+
+  immEnd();
+}
+
 static bool paint_use_2d_cursor(ePaintMode mode)
 {
   if (mode >= PAINT_MODE_TEXTURE_3D) {
@@ -1516,6 +1580,24 @@ static void paint_draw_cursor(bContext *C, int x, int y, void *UNUSED(unused))
             }
           }
 
+          if (brush->sculpt_tool == SCULPT_TOOL_MULTIPLANE_SCRAPE &&
+              brush->flag2 & BRUSH_MULTIPLANE_SCRAPE_PLANES_PREVIEW && !ss->cache->first_time) {
+            GPU_matrix_push_projection();
+            ED_view3d_draw_setup_view(CTX_wm_window(C),
+                                      CTX_data_depsgraph_pointer(C),
+                                      CTX_data_scene(C),
+                                      ar,
+                                      CTX_wm_view3d(C),
+                                      NULL,
+                                      NULL,
+                                      NULL);
+            GPU_matrix_push();
+            GPU_matrix_mul(vc.obact->obmat);
+            sculpt_multiplane_scrape_preview_draw(pos, ss, outline_col, outline_alpha);
+            GPU_matrix_pop();
+            GPU_matrix_pop_projection();
+          }
+
           wmWindowViewport(win);
         }
       }