Fix T59595: Grease Pencil and CameraView

The perspective effect deformed the stroke. Now when you are in camera view and the lock axis is not enabled, the stroke is reprojected flat over the view to remove any deformation.

Also fixed reproject operator to use the origin set in topbar and not cursor 3D always.

1 files changed, 43 insertions, 3 deletions

diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil/gpencil_utils.c
index fcfe6132948..22a7e68d825 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil/gpencil_utils.c
@@ -522,6 +522,9 @@ void gp_point_conversion_init(bContext *C, GP_SpaceConversion *r_gsc)
 	unit_m4(r_gsc->mat);
 
 	/* store settings */
+	r_gsc->scene = CTX_data_scene(C);
+	r_gsc->ob = CTX_data_active_object(C);
+
 	r_gsc->sa = sa;
 	r_gsc->ar = ar;
 	r_gsc->v2d = &ar->v2d;
@@ -738,8 +741,11 @@ void gp_point_to_xy_fl(
 bool gp_point_xy_to_3d(GP_SpaceConversion *gsc, Scene *scene, const float screen_co[2], float r_out[3])
 {
 	const RegionView3D *rv3d = gsc->ar->regiondata;
-	float *rvec = scene->cursor.location;
-	float ref[3] = {rvec[0], rvec[1], rvec[2]};
+	float rvec[3];
+
+	ED_gp_get_drawing_reference(scene, gsc->ob, gsc->gpl,
+		scene->toolsettings->gpencil_v3d_align, rvec);
+
 	float zfac = ED_view3d_calc_zfac(rv3d, rvec, NULL);
 
 	float mval_f[2], mval_prj[2];
@@ -747,7 +753,7 @@ bool gp_point_xy_to_3d(GP_SpaceConversion *gsc, Scene *scene, const float screen
 
 	copy_v2_v2(mval_f, screen_co);
 
-	if (ED_view3d_project_float_global(gsc->ar, ref, mval_prj, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
+	if (ED_view3d_project_float_global(gsc->ar, rvec, mval_prj, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
 		sub_v2_v2v2(mval_f, mval_prj, mval_f);
 		ED_view3d_win_to_delta(gsc->ar, mval_f, dvec, zfac);
 		sub_v3_v3v3(r_out, rvec, dvec);
@@ -838,6 +844,40 @@ void ED_gp_get_drawing_reference(
 	}
 }
 
+void ED_gpencil_project_stroke_to_view(bContext *C, bGPDlayer *gpl, bGPDstroke *gps)
+{
+	Scene *scene = CTX_data_scene(C);
+	Depsgraph *depsgraph = CTX_data_depsgraph(C);
+	Object *ob = CTX_data_active_object(C);
+	bGPdata *gpd = (bGPdata *)ob->data;
+	GP_SpaceConversion gsc = { NULL };
+
+	bGPDspoint *pt;
+	int i;
+	float diff_mat[4][4];
+	float inverse_diff_mat[4][4];
+
+	/* init space conversion stuff */
+	gp_point_conversion_init(C, &gsc);
+
+	ED_gpencil_parent_location(depsgraph, ob, gpd, gpl, diff_mat);
+	invert_m4_m4(inverse_diff_mat, diff_mat);
+
+	/* Adjust each point */
+	for (i = 0, pt = gps->points; i < gps->totpoints; i++, pt++) {
+		float xy[2];
+
+		bGPDspoint pt2;
+		gp_point_to_parent_space(pt, diff_mat, &pt2);
+		gp_point_to_xy_fl(&gsc, gps, &pt2, &xy[0], &xy[1]);
+
+		/* Planar - All on same plane parallel to the viewplane */
+		gp_point_xy_to_3d(&gsc, scene, xy, &pt->x);
+
+		/* Unapply parent corrections */
+		mul_m4_v3(inverse_diff_mat, &pt->x);
+	}
+}
 
 /**
  * Reproject all points of the stroke to a plane locked to axis to avoid stroke offset