GP: Fix precision issue with Circle and Arc tools

Differential Revision: https://developer.blender.org/D4030

3 files changed, 67 insertions, 26 deletions

diff --git a/source/blender/editors/gpencil/gpencil_intern.h b/source/blender/editors/gpencil/gpencil_intern.h
index 5db5c0f2571..6d05afa0e8d 100644
--- a/source/blender/editors/gpencil/gpencil_intern.h
+++ b/source/blender/editors/gpencil/gpencil_intern.h
@@ -228,6 +228,13 @@ void gp_stroke_convertcoords_tpoint(
         bGPDlayer *gpl, const struct tGPspoint *point2D,
         float *depth, float out[3]);
 
+/* helper to convert 2d to 3d for primitive. See: D4030 */
+void gp_stroke_convertcoords_tpoint_primitive(
+        struct Scene *scene, struct ARegion *ar,
+        struct Object *ob,
+        bGPDlayer *gpl, const struct tPGPspoint *point2D,
+        float out[3]);
+
 /* Poll Callbacks ------------------------------------ */
 /* gpencil_utils.c */
 
diff --git a/source/blender/editors/gpencil/gpencil_primitive.c b/source/blender/editors/gpencil/gpencil_primitive.c
index d22e9736172..9d36c1f3963 100644
--- a/source/blender/editors/gpencil/gpencil_primitive.c
+++ b/source/blender/editors/gpencil/gpencil_primitive.c
@@ -260,37 +260,37 @@ static void gpencil_primitive_status_indicators(bContext *C, tGPDprimitive *tgpi
 /* ----------------------- */
 
 /* create a rectangle */
-static void gp_primitive_rectangle(tGPDprimitive *tgpi, tGPspoint *points2D)
+static void gp_primitive_rectangle(tGPDprimitive *tgpi, tPGPspoint *points2D)
 {
 	BLI_assert(tgpi->tot_edges == 4);
 
-	points2D[0].x = tgpi->top[0];
-	points2D[0].y = tgpi->top[1];
+	points2D[0].x = (float)tgpi->top[0];
+	points2D[0].y = (float)tgpi->top[1];
 
-	points2D[1].x = tgpi->bottom[0];
-	points2D[1].y = tgpi->top[1];
+	points2D[1].x = (float)tgpi->bottom[0];
+	points2D[1].y = (float)tgpi->top[1];
 
-	points2D[2].x = tgpi->bottom[0];
-	points2D[2].y = tgpi->bottom[1];
+	points2D[2].x = (float)tgpi->bottom[0];
+	points2D[2].y = (float)tgpi->bottom[1];
 
-	points2D[3].x = tgpi->top[0];
-	points2D[3].y = tgpi->bottom[1];
+	points2D[3].x = (float)tgpi->top[0];
+	points2D[3].y = (float)tgpi->bottom[1];
 }
 
 /* create a line */
-static void gp_primitive_line(tGPDprimitive *tgpi, tGPspoint *points2D)
+static void gp_primitive_line(tGPDprimitive *tgpi, tPGPspoint *points2D)
 {
 	BLI_assert(tgpi->tot_edges == 2);
 
-	points2D[0].x = tgpi->top[0];
-	points2D[0].y = tgpi->top[1];
+	points2D[0].x = (float)tgpi->top[0];
+	points2D[0].y = (float)tgpi->top[1];
 
-	points2D[1].x = tgpi->bottom[0];
-	points2D[1].y = tgpi->bottom[1];
+	points2D[1].x = (float)tgpi->bottom[0];
+	points2D[1].y = (float)tgpi->bottom[1];
 }
 
 /* create an arc */
-static void gp_primitive_arc(tGPDprimitive *tgpi, tGPspoint *points2D)
+static void gp_primitive_arc(tGPDprimitive *tgpi, tPGPspoint *points2D)
 {
 	const int totpoints = tgpi->tot_edges;
 	const float step = M_PI_2 / (float)(totpoints - 1);
@@ -313,15 +313,15 @@ static void gp_primitive_arc(tGPDprimitive *tgpi, tGPspoint *points2D)
 	length[1] = end[1] - start[1];
 
 	for (int i = 0; i < totpoints; i++) {
-		tGPspoint *p2d = &points2D[i];
-		p2d->x = (int)(start[0] + sinf(a) * length[0]);
-		p2d->y = (int)(end[1] - cosf(a) * length[1]);
+		tPGPspoint *p2d = &points2D[i];
+		p2d->x = (start[0] + sinf(a) * length[0]);
+		p2d->y = (end[1] - cosf(a) * length[1]);
 		a += step;
 	}
 }
 
 /* create a circle */
-static void gp_primitive_circle(tGPDprimitive *tgpi, tGPspoint *points2D)
+static void gp_primitive_circle(tGPDprimitive *tgpi, tPGPspoint *points2D)
 {
 	const int totpoints = tgpi->tot_edges;
 	const float step = (2.0f * M_PI) / (float)(totpoints);
@@ -336,10 +336,9 @@ static void gp_primitive_circle(tGPDprimitive *tgpi, tGPspoint *points2D)
 	radius[1] = fabsf(((tgpi->bottom[1] - tgpi->top[1]) / 2.0f));
 
 	for (int i = 0; i < totpoints; i++) {
-		tGPspoint *p2d = &points2D[i];
-
-		p2d->x = (int)(center[0] + cosf(a) * radius[0]);
-		p2d->y = (int)(center[1] + sinf(a) * radius[1]);
+		tPGPspoint *p2d = &points2D[i];
+		p2d->x = (center[0] + cosf(a) * radius[0]);
+		p2d->y = (center[1] + sinf(a) * radius[1]);
 		a += step;
 	}
 }
@@ -360,7 +359,7 @@ static void gp_primitive_update_strokes(bContext *C, tGPDprimitive *tgpi)
 	gps->totpoints = tgpi->tot_edges;
 
 	/* compute screen-space coordinates for points */
-	tGPspoint *points2D = MEM_callocN(sizeof(tGPspoint) * tgpi->tot_edges, "gp primitive points2D");
+	tPGPspoint *points2D = MEM_callocN(sizeof(tPGPspoint) * tgpi->tot_edges, "gp primitive points2D");
 	switch (tgpi->type) {
 		case GP_STROKE_BOX:
 			gp_primitive_rectangle(tgpi, points2D);
@@ -385,10 +384,10 @@ static void gp_primitive_update_strokes(bContext *C, tGPDprimitive *tgpi)
 	/* convert screen-coordinates to 3D coordinates */
 	for (int i = 0; i < gps->totpoints; i++) {
 		bGPDspoint *pt = &gps->points[i];
-		tGPspoint *p2d = &points2D[i];
+		tPGPspoint *p2d = &points2D[i];
 
 		/* convert screen-coordinates to 3D coordinates */
-		gp_stroke_convertcoords_tpoint(tgpi->scene, tgpi->ar, tgpi->ob, tgpi->gpl, p2d, NULL, &pt->x);
+		gp_stroke_convertcoords_tpoint_primitive(tgpi->scene, tgpi->ar, tgpi->ob, tgpi->gpl, p2d, &pt->x);
 
 		pt->pressure = 1.0f;
 		pt->strength = tgpi->brush->gpencil_settings->draw_strength;
diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil/gpencil_utils.c
index 73be10a537f..4d16f842fa3 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil/gpencil_utils.c
@@ -807,6 +807,41 @@ void gp_stroke_convertcoords_tpoint(
 }
 
 /**
+ * Convert primitive tPGPspoint (temporary 2D/screenspace point data used by GP primitive operators)
+ * to 3D coordinates.
+ *
+ * See: D4030
+ */
+void gp_stroke_convertcoords_tpoint_primitive(
+	Scene *scene, ARegion *ar,
+	Object *ob, bGPDlayer *gpl,
+	const tPGPspoint *point2D,
+	float r_out[3])
+{
+	ToolSettings *ts = scene->toolsettings;
+
+	float mval_f[2] = { point2D->x, point2D->y };
+	float mval_prj[2];
+	float rvec[3], dvec[3];
+	float zfac;
+
+	/* Current method just converts each point in screen-coordinates to
+		* 3D-coordinates using the 3D-cursor as reference.
+		*/
+	ED_gp_get_drawing_reference(scene, ob, gpl, ts->gpencil_v3d_align, rvec);
+	zfac = ED_view3d_calc_zfac(ar->regiondata, rvec, NULL);
+
+	if (ED_view3d_project_float_global(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(ar, mval_f, dvec, zfac);
+		sub_v3_v3v3(r_out, rvec, dvec);
+	}
+	else {
+		zero_v3(r_out);
+	}
+}
+
+/**
  * Get drawing reference point for conversion or projection of the stroke
  * \param[out] r_vec : Reference point found
  */