GPencil: Implement Opacity transform

Add Shift+F to transform points opacity in Edit mode

release/scripts/presets/keyconfig/keymap_data/blender_default.py

@@ -3023,6 +3023,8 @@ def km_grease_pencil_stroke_edit_mode(params):
         ("transform.shear", {"type": 'S', "value": 'PRESS', "shift": True, "ctrl": True, "alt": True}, None),
         ("transform.transform", {"type": 'S', "value": 'PRESS', "alt": True},
          {"properties": [("mode", 'GPENCIL_SHRINKFATTEN')]}),
+        ("transform.transform", {"type": 'F', "value": 'PRESS', "shift": True},
+         {"properties": [("mode", 'GPENCIL_OPACITY')]}),
         # Proportonal editing
         *_template_items_proportional_editing(connected=True),
         # Add menu

source/blender/editors/include/ED_transform.h

@@ -82,6 +82,7 @@ enum TfmMode {
 	TFM_SEQ_SLIDE,
 	TFM_BONE_ENVELOPE_DIST,
 	TFM_NORMAL_ROTATION,
+	TFM_GPENCIL_OPACITY,
 };
 
 /* TRANSFORM CONTEXTS */

source/blender/editors/transform/transform.c

@@ -205,6 +205,9 @@ static void applyAlign(TransInfo *t, const int mval[2]);
 
 static void initSeqSlide(TransInfo *t);
 static void applySeqSlide(TransInfo *t, const int mval[2]);
+
+static void initGPOpacity(TransInfo *t);
+static void applyGPOpacity(TransInfo *t, const int mval[2]);
 /* end transform callbacks */
 
 
@@ -2613,6 +2616,9 @@ bool initTransform(bContext *C, TransInfo *t, wmOperator *op, const wmEvent *eve
 		case TFM_NORMAL_ROTATION:
 			initNormalRotation(t);
 			break;
+		case TFM_GPENCIL_OPACITY:
+			initGPOpacity(t);
+			break;
 	}
 
 	if (t->state == TRANS_CANCEL) {
@@ -5525,6 +5531,84 @@ static void applyGPShrinkFatten(TransInfo *t, const int UNUSED(mval[2]))
 }
 /** \} */
 
+/* -------------------------------------------------------------------- */
+/* Transform (GPencil Opacity) */
+
+/** \name Transform GPencil Strokes Opacity
+ * \{ */
+
+static void initGPOpacity(TransInfo *t)
+{
+	t->mode = TFM_GPENCIL_OPACITY;
+	t->transform = applyGPOpacity;
+
+	initMouseInputMode(t, &t->mouse, INPUT_SPRING);
+
+	t->idx_max = 0;
+	t->num.idx_max = 0;
+	t->snap[0] = 0.0f;
+	t->snap[1] = 0.1f;
+	t->snap[2] = t->snap[1] * 0.1f;
+
+	copy_v3_fl(t->num.val_inc, t->snap[1]);
+	t->num.unit_sys = t->scene->unit.system;
+	t->num.unit_type[0] = B_UNIT_NONE;
+
+	t->flag |= T_NO_ZERO;
+#ifdef USE_NUM_NO_ZERO
+	t->num.val_flag[0] |= NUM_NO_ZERO;
+#endif
+
+	t->flag |= T_NO_CONSTRAINT;
+}
+
+static void applyGPOpacity(TransInfo *t, const int UNUSED(mval[2]))
+{
+	float ratio;
+	int i;
+	char str[UI_MAX_DRAW_STR];
+
+	ratio = t->values[0];
+
+	snapGridIncrement(t, &ratio);
+
+	applyNumInput(&t->num, &ratio);
+
+	t->values[0] = ratio;
+
+	/* header print for NumInput */
+	if (hasNumInput(&t->num)) {
+		char c[NUM_STR_REP_LEN];
+
+		outputNumInput(&(t->num), c, &t->scene->unit);
+		BLI_snprintf(str, sizeof(str), IFACE_("Opacity: %s"), c);
+	}
+	else {
+		BLI_snprintf(str, sizeof(str), IFACE_("Opacity: %3f"), ratio);
+	}
+
+	FOREACH_TRANS_DATA_CONTAINER(t, tc) {
+		TransData *td = tc->data;
+		for (i = 0; i < tc->data_len; i++, td++) {
+			if (td->flag & TD_NOACTION)
+				break;
+
+			if (td->flag & TD_SKIP)
+				continue;
+
+			if (td->val) {
+				*td->val = td->ival * ratio;
+				/* apply PET */
+				*td->val = (*td->val * td->factor) + ((1.0f - td->factor) * td->ival);
+				CLAMP(*td->val, 0.0f, 1.0f);
+			}
+		}
+	}
+
+	ED_area_status_text(t->sa, str);
+}
+/** \} */
+
 
 /* -------------------------------------------------------------------- */
 /* Transform (Push/Pull) */

source/blender/editors/transform/transform_conversions.c

@@ -8567,8 +8567,14 @@ static void createTransGPencil(bContext *C, TransInfo *t)
 									 * but never for scale or mirror
 									 */
 									if ((t->mode != TFM_RESIZE) && (t->mode != TFM_MIRROR)) {
-										td->val = &pt->pressure;
-										td->ival = pt->pressure;
+										if (t->mode != TFM_GPENCIL_OPACITY) {
+											td->val = &pt->pressure;
+											td->ival = pt->pressure;
+										}
+										else {
+											td->val = &pt->strength;
+											td->ival = pt->strength;
+										}
 									}
 
 									/* screenspace needs special matrices... */

source/blender/editors/transform/transform_ops.c

@@ -155,6 +155,7 @@ const EnumPropertyItem rna_enum_transform_mode_types[] =
 	{TFM_ALIGN, "ALIGN", 0, "Align", ""},
 	{TFM_EDGE_SLIDE, "EDGESLIDE", 0, "Edge Slide", ""},
 	{TFM_SEQ_SLIDE, "SEQSLIDE", 0, "Sequence Slide", ""},
+	{TFM_GPENCIL_OPACITY, "GPENCIL_OPACITY", 0, "GPencil_Opacity", ""},
 	{0, NULL, 0, NULL, NULL},
 };