Falloff curve. (WIP)

3 files changed, 93 insertions, 3 deletions

diff --git a/source/blender/gpu/shaders/sculpt_paint/infos/sculpt_paint_image_info.hh b/source/blender/gpu/shaders/sculpt_paint/infos/sculpt_paint_image_info.hh
index 97eed0237f4..838a198a367 100644
--- a/source/blender/gpu/shaders/sculpt_paint/infos/sculpt_paint_image_info.hh
+++ b/source/blender/gpu/shaders/sculpt_paint/infos/sculpt_paint_image_info.hh
@@ -35,12 +35,35 @@ GPU_SHADER_CREATE_INFO(sculpt_paint_image_merge_compute)
 GPU_SHADER_CREATE_INFO(sculpt_paint_test_sphere).define("BRUSH_TEST_SPHERE");
 GPU_SHADER_CREATE_INFO(sculpt_paint_test_circle).define("BRUSH_TEST_CIRCLE");
 
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_custom).define("BRUSH_CURVE_PRESET 0");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_smooth).define("BRUSH_CURVE_PRESET 1");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_sphere).define("BRUSH_CURVE_PRESET 2");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_root).define("BRUSH_CURVE_PRESET 3");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_sharp).define("BRUSH_CURVE_PRESET 4");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_lin).define("BRUSH_CURVE_PRESET 5");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_pow4).define("BRUSH_CURVE_PRESET 6");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_invsquare).define("BRUSH_CURVE_PRESET 7");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_constant).define("BRUSH_CURVE_PRESET 8");
+GPU_SHADER_CREATE_INFO(sculpt_paint_falloff_smoother).define("BRUSH_CURVE_PRESET 9");
+
 #define SCULPT_PAINT_FINAL_VARIATION(name, ...) \
   GPU_SHADER_CREATE_INFO(name).additional_info(__VA_ARGS__).do_static_compilation(true);
 
+#define SCULPT_PAINT_CURVE_VARIATION(name, ...) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_custom, "sculpt_paint_falloff_custom", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_smooth, "sculpt_paint_falloff_smooth", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_sphere, "sculpt_paint_falloff_sphere", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_root, "sculpt_paint_falloff_root", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_sharp, "sculpt_paint_falloff_sharp", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_lin, "sculpt_paint_falloff_lin", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_pow4, "sculpt_paint_falloff_pow4", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_invsquare, "sculpt_paint_falloff_invsquare", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_constant, "sculpt_paint_falloff_constant", __VA_ARGS__) \
+  SCULPT_PAINT_FINAL_VARIATION(name##_smoother, "sculpt_paint_falloff_smoother", __VA_ARGS__)
+
 #define SCULPT_PAINT_TEST_VARIATIONS(name, ...) \
-  SCULPT_PAINT_FINAL_VARIATION(name##_sphere, "sculpt_paint_test_sphere", __VA_ARGS__) \
-  SCULPT_PAINT_FINAL_VARIATION(name##_circle, "sculpt_paint_test_circle", __VA_ARGS__)
+  SCULPT_PAINT_CURVE_VARIATION(name##_sphere, "sculpt_paint_test_sphere", __VA_ARGS__) \
+  SCULPT_PAINT_CURVE_VARIATION(name##_circle, "sculpt_paint_test_circle", __VA_ARGS__)
 
 SCULPT_PAINT_TEST_VARIATIONS(sculpt_paint_image, "sculpt_paint_image_compute")
 
diff --git a/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_comp.glsl b/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_comp.glsl
index e85e894a25b..2d64d9f2699 100644
--- a/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_comp.glsl
+++ b/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_comp.glsl
@@ -47,7 +47,9 @@ void main()
           color_read = true;
         }
         // TODO: blend with color...
-        color = max(color, paint_brush_buf.color);
+        float factor = SCULPT_hardness_factor(distance, step_data.hardness, step_data.radius);
+        float curve_factor = SCULPT_curve_strength(factor, BRUSH_CURVE_PRESET);
+        color = max(color, paint_brush_buf.color * curve_factor);
       }
     }
     if (color_read) {
diff --git a/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_lib.glsl b/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_lib.glsl
index 159e24112d8..a8b008ca7eb 100644
--- a/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_lib.glsl
+++ b/source/blender/gpu/shaders/sculpt_paint/sculpt_paint_image_lib.glsl
@@ -1,3 +1,66 @@
+
+/* -------------------------------------------------------------------- */
+/** \name Brush testing
+ * \{ */
+
+float SCULPT_curve_strength(float factor, int curve_type)
+{
+  if (factor > 1.0) {
+    return 0.0;
+  }
+  float p = 1.0 - factor;
+
+  switch (curve_type) {
+    case 0 /*BRUSH_CURVE_CUSTOM*/:
+      return factor;
+    case 1 /*BRUSH_CURVE_SMOOTH*/:
+      return 3.0 * p * p - 2.0 * p * p * p;
+    case 2 /*BRUSH_CURVE_SPHERE*/:
+      return sqrt(2.0 * p - p * p);
+    case 3 /*BRUSH_CURVE_ROOT*/:
+      return sqrt(p);
+    case 4 /*BRUSH_CURVE_SHARP*/:
+      return p * p;
+    case 5 /*BRUSH_CURVE_LIN*/:
+      return p;
+    case 6 /*BRUSH_CURVE_POW4*/:
+      return p * p * p * p;
+    case 7 /*BRUSH_CURVE_INVSQUARE*/:
+      return p * (2.0 - p);
+    case 8 /*BRUSH_CURVE_CONSTANT*/:
+      return 1.0;
+    case 9 /*BRUSH_CURVE_SMOOTHER*/:
+      return p * p * p * (p * (p * 6.0 - 15.0) + 10.0);
+    default:
+      return factor;
+  }
+
+  return factor;
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Brush testing
+ * \{ */
+float SCULPT_hardness_factor(float dist, float hardness, float radius)
+{
+  float p = dist / radius;
+  if (p < hardness) {
+    return 0.0;
+  }
+  else if (hardness >= 1.0) {
+    return 1.0;
+  }
+  return (p - hardness / (1.0 - hardness));
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Brush testing
+ * \{ */
+
 bool SCULPT_brush_test_sphere(PaintBrushTestData test_data,
                               PaintStepData step_data,
                               vec3 co,
@@ -27,6 +90,8 @@ bool SCULPT_brush_test_circle(PaintBrushTestData test_data,
   return SCULPT_brush_test_sphere(test_data, step_data, proj, dist);
 }
 
+/** \} */
+
 void SCULPT_get_row_pos_and_delta(vec3 co1,
                                   vec3 co2,
                                   vec3 co3,