GPencil: Change interpolate stroke factor

Now the factor works similar to other Blender areas to make the factor
more consistent for artists. The value 0% means equal to original
stroke, 100% equal to final stroke (50% means half way). Any value below
0% or greater than 100% create an overshoot of the stroke.

diff --git a/source/blender/editors/gpencil/gpencil_edit.c b/source/blender/editors/gpencil/gpencil_edit.c
index 3d0323dbfb187694c37b6163fec330808205cb30..cce22ba9e170c336a5ca6d14cabd228d1d8eac1c 100644 (file)
--- a/source/blender/editors/gpencil/gpencil_edit.c
+++ b/source/blender/editors/gpencil/gpencil_edit.c
@@ -2076,6 +2076,12 @@ static void gp_interpolate_set_points(bContext *C, tGPDinterpolate *tgpi)
        bGPDstroke *gps_from, *gps_to, *new_stroke;
        int fFrame;
 
+       /* save initial factor for active layer to define shift limits */
+       tgpi->init_factor = (float)(tgpi->cframe - active_gpl->actframe->framenum) / (active_gpl->actframe->next->framenum - active_gpl->actframe->framenum + 1);
+       /* limits are 100% below 0 and 100% over the 100% */
+       tgpi->low_limit = -1.0f - tgpi->init_factor;
+       tgpi->high_limit = 2.0f - tgpi->init_factor;
+
        /* set layers */
        for (gpl = gpd->layers.first; gpl; gpl = gpl->next) {
                /* all layers or only active */
@@ -2099,7 +2105,7 @@ static void gp_interpolate_set_points(bContext *C, tGPDinterpolate *tgpi)
                tgpil->interFrame = MEM_callocN(sizeof(bGPDframe), "bGPDframe");
                tgpil->interFrame->framenum = tgpi->cframe;
 
-               /* get interpolation factor */
+               /* get interpolation factor by layer (usually must be equal for all layers, but not sure) */
                tgpil->factor = (float)(tgpi->cframe - tgpil->prevFrame->framenum) / (tgpil->nextFrame->framenum - tgpil->prevFrame->framenum + 1);
                /* create new strokes data with interpolated points reading original stroke */
                for (gps_from = tgpil->prevFrame->strokes.first; gps_from; gps_from = gps_from->next) {
@@ -2159,13 +2165,13 @@ static void gpencil_mouse_update_shift(tGPDinterpolate *tgpi, wmOperator *op, co
        float mid = (float)(tgpi->ar->winx - tgpi->ar->winrct.xmin) / 2.0f;
        float mpos = event->x - tgpi->ar->winrct.xmin;
        if (mpos >= mid) {
-               tgpi->shift = (mpos - mid) / mid;
+               tgpi->shift = ((mpos - mid) * tgpi->high_limit) / mid;
        }
        else {
-               tgpi->shift = -1.0f * (1.0f - (mpos / mid));
+               tgpi->shift = tgpi->low_limit - ((mpos * tgpi->low_limit) / mid);
        }
 
-       CLAMP(tgpi->shift, -1.0f, 1.0f);
+       CLAMP(tgpi->shift, tgpi->low_limit, tgpi->high_limit);
        RNA_float_set(op->ptr, "shift", tgpi->shift);
 }
 
@@ -2185,7 +2191,7 @@ static void gpencil_interpolate_status_indicators(tGPDinterpolate *p)
                BLI_snprintf(status_str, sizeof(status_str), "%s: %s", msg_str, str_offs);
        }
        else {
-               BLI_snprintf(status_str, sizeof(status_str), "%s: %d", msg_str, (int)(p->shift * 100.0f));
+               BLI_snprintf(status_str, sizeof(status_str), "%s: %d %%", msg_str, (int)((p->init_factor + p->shift)  * 100.0f));
        }
 
        ED_area_headerprint(p->sa, status_str);
@@ -2343,13 +2349,13 @@ static int gpencil_interpolate_invoke(bContext *C, wmOperator *op, const wmEvent
 
        /* cannot interpolate if not between 2 frames */
        if ((gpl->actframe == NULL) || (gpl->actframe->next == NULL)) {
-               BKE_report(op->reports, RPT_ERROR, "Interpolation requires to be between two grease pencil frames");
+               BKE_report(op->reports, RPT_ERROR, "Interpolation requires to be between two grease pencil frames in active layer");
                return OPERATOR_CANCELLED;
        }
 
        /* cannot interpolate in extremes */
        if ((gpl->actframe->framenum == scene->r.cfra) || (gpl->actframe->next->framenum == scene->r.cfra)) {
-               BKE_report(op->reports, RPT_ERROR, "Interpolation requires to be between two grease pencil frames");
+               BKE_report(op->reports, RPT_ERROR, "Interpolation requires to be between two grease pencil frames in active layer");
                return OPERATOR_CANCELLED;
        }
 
@@ -2444,7 +2450,7 @@ static int gpencil_interpolate_modal(bContext *C, wmOperator *op, const wmEvent
                case WHEELUPMOUSE:
                {
                        tgpi->shift = tgpi->shift + 0.01f;
-                       CLAMP(tgpi->shift, -1.0f, 1.0f);
+                       CLAMP(tgpi->shift, tgpi->low_limit, tgpi->high_limit);
                        RNA_float_set(op->ptr, "shift", tgpi->shift);
                        /* update screen */
                        gpencil_interpolate_update(C, op, tgpi);
@@ -2453,7 +2459,7 @@ static int gpencil_interpolate_modal(bContext *C, wmOperator *op, const wmEvent
                case WHEELDOWNMOUSE:
                {
                        tgpi->shift = tgpi->shift - 0.01f;
-                       CLAMP(tgpi->shift, -1.0f, 1.0f);
+                       CLAMP(tgpi->shift, tgpi->low_limit, tgpi->high_limit);
                        RNA_float_set(op->ptr, "shift", tgpi->shift);
                        /* update screen */
                        gpencil_interpolate_update(C, op, tgpi);
@@ -2473,13 +2479,16 @@ static int gpencil_interpolate_modal(bContext *C, wmOperator *op, const wmEvent
                default:
                        if ((event->val == KM_PRESS) && handleNumInput(C, &tgpi->num, event)) {
                                float value;
+                               float factor = tgpi->init_factor;
 
                                /* Grab shift from numeric input, and store this new value (the user see an int) */
-                               value = tgpi->shift * 100.0f;
+                               value = (factor + tgpi->shift) * 100.0f;
                                applyNumInput(&tgpi->num, &value);
-
                                tgpi->shift = value / 100.0f;
-                               CLAMP(tgpi->shift, -1.0f, 1.0f);
+                               /* recalculate the shift to get the right value in the frame scale */
+                               tgpi->shift = tgpi->shift - factor;
+
+                               CLAMP(tgpi->shift, tgpi->low_limit, tgpi->high_limit);
                                RNA_float_set(op->ptr, "shift", tgpi->shift);
 
                                /* update screen */

diff --git a/source/blender/editors/include/ED_gpencil.h b/source/blender/editors/include/ED_gpencil.h
index e53f29ef6b72ac1a15ae6b7a11cb070dc8923fd3..bc93b5622cb2a70bfb1c72859f05047501b7608b 100644 (file)
--- a/source/blender/editors/include/ED_gpencil.h
+++ b/source/blender/editors/include/ED_gpencil.h
@@ -73,7 +73,10 @@ typedef struct tGPDinterpolate {
 
        int cframe;                /* current frame number */
        ListBase ilayers;   /* (tGPDinterpolate_layer) layers to be interpolated */
-       float shift;        /* -1/1 value for determining the displacement influence */
+       float shift;        /* value for determining the displacement influence */
+       float init_factor;  /* initial interpolation factor for active layer */
+       float low_limit;    /* shift low limit (-100%) */
+       float high_limit;   /* shift upper limit (200%) */
        int flag;           /* flag from toolsettings */
 
        NumInput num;       /* numeric input */