[Bf-blender-cvs] [141f2c1] wiggly-widgets: Use better algorithm for arrow widget back transform.

[Antony Riakiotakis]

Commit: 141f2c1d5c3f8831d06aea944c530bf66545589d
Author: Antony Riakiotakis
Date:   Mon Nov 17 12:31:42 2014 +0100
Branches: wiggly-widgets
https://developer.blender.org/rB141f2c1d5c3f8831d06aea944c530bf66545589d

Use better algorithm for arrow widget back transform.

We now use plane/line intersection which seems to work quite well and
agrees to great extent with the transform system as well. There still
some small discrepancy but may also be related to scaling.

===================================================================

M	source/blender/windowmanager/intern/wm_generic_widgets.c

===================================================================

diff --git a/source/blender/windowmanager/intern/wm_generic_widgets.c b/source/blender/windowmanager/intern/wm_generic_widgets.c
index 11d9a98..460ff1c 100644
--- a/source/blender/windowmanager/intern/wm_generic_widgets.c
+++ b/source/blender/windowmanager/intern/wm_generic_widgets.c
@@ -227,10 +227,11 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 	RegionView3D *rv3d = ar->regiondata;
 
 	float orig_origin[4];
+	float viewvec[3], tangent[3], plane[3];
 	float offset[4];
 	float m_diff[2];
 	float dir_2d[2], dir2d_final[2];
-	float fac;
+	float fac, zfac;
 	float facdir = 1.0f;
 
 	copy_v3_v3(orig_origin, data->orig_origin);
@@ -238,6 +239,8 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 	add_v3_v3v3(offset, orig_origin, arrow->direction);
 	offset[3] = 1.0f;
 
+	zfac = ED_view3d_calc_zfac(rv3d, orig_origin, NULL);
+
 	/* multiply to projection space */
 	mul_m4_v4(rv3d->persmat, orig_origin);
 	mul_m4_v4(rv3d->persmat, offset);
@@ -245,11 +248,10 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 	mul_v4_fl(orig_origin, 1.0f/orig_origin[3]);
 	mul_v4_fl(offset, 1.0f/offset[3]);
 	sub_v2_v2v2(dir_2d, offset, orig_origin);
+	dir_2d[0] *= ar->winx;
+	dir_2d[1] *= ar->winy;
 	normalize_v2(dir_2d);
 
-	dir_2d[0] *= BLI_rcti_size_x(&ar->winrct) * 0.5f;
-	dir_2d[1] *= BLI_rcti_size_y(&ar->winrct) * 0.5f;
-
 	/* find mouse difference */
 	m_diff[0] = event->mval[0] - data->orig_mouse[0];
 	m_diff[1] = event->mval[1] - data->orig_mouse[1];
@@ -257,24 +259,25 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 	/* project the displacement on the screen space arrow direction */
 	project_v2_v2v2(dir2d_final, m_diff, dir_2d);
 
-	dir2d_final[0] /= (BLI_rcti_size_x(&ar->winrct) * 0.5f);
-	dir2d_final[1] /= (BLI_rcti_size_y(&ar->winrct) * 0.5f);
+	ED_view3d_win_to_delta(ar, dir2d_final, offset, zfac);
 
-	add_v2_v2(orig_origin, dir2d_final);
+	add_v3_v3v3(orig_origin, offset, data->orig_origin);
 
-	/* project back to world space and find world space displacement direction */
-	mul_m4_v4(rv3d->persinv, orig_origin);
-	mul_v4_fl(orig_origin, 1.0f/orig_origin[3]);
+	/* calculate view vector */
+	if (rv3d->is_persp) {
+		sub_v3_v3v3(viewvec, orig_origin, rv3d->viewinv[3]);
+	}
+	else {
+		copy_v3_v3(viewvec, rv3d->viewinv[2]);
+	}
 
-	sub_v3_v3(orig_origin, data->orig_origin);
+	/* now find a plane parallel to the view vector so we can intersect with the arrow direction */
+	cross_v3_v3v3(tangent, viewvec, offset);
+	cross_v3_v3v3(plane, tangent, viewvec);
+	fac = dot_v3v3(plane, offset) / dot_v3v3(arrow->direction, plane);
 
-	/* reuse offset, project direction to displacement */
-	project_v3_v3v3(offset, arrow->direction, orig_origin);
-	fac = len_v3(orig_origin) / len_v3(offset);
-	if (dot_v3v3(offset, orig_origin) < 0.0f)
-		facdir = -1.0;
-	fac *= facdir;
-	mul_v3_v3fl(orig_origin, offset, fac);
+	facdir = (fac < 0.0) ? -1.0 : 1.0;
+	mul_v3_v3fl(offset, arrow->direction, fac);
 
 	/* set the property for the operator and call its modal function */
 	if (op && widget->propname) {
@@ -283,7 +286,7 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 	else if (widget->prop) {
 		float value;
 
-		value = data->orig_offset + facdir / widget->scale * len_v3(orig_origin);
+		value = data->orig_offset + facdir / widget->scale * len_v3(offset);
 		if (arrow->style & UI_ARROW_STYLE_CONSTRAINED) {
 			if (arrow->style & UI_ARROW_STYLE_INVERTED)
 				value = arrow->min + arrow->range - (value * arrow->range / ARROW_RANGE);
@@ -294,7 +297,6 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 		RNA_property_float_set(widget->ptr, widget->prop, value);
 		RNA_property_update(C, widget->ptr, widget->prop);
 
-
 		/* accounts for clamping properly */
 		if (arrow->style & UI_ARROW_STYLE_CONSTRAINED) {
 			if (arrow->style & UI_ARROW_STYLE_INVERTED)
@@ -306,7 +308,7 @@ static int widget_arrow_handler(struct bContext *C, const struct wmEvent *event,
 			arrow->offset = RNA_property_float_get(widget->ptr, widget->prop);
 	}
 	else {
-		arrow->offset = facdir / widget->scale * len_v3(orig_origin);
+		arrow->offset = facdir / widget->scale * len_v3(offset);
 	}
 
 	/* tag the region for redraw */