Don't update xsections if unnecessary.

1 files changed, 12 insertions, 1 deletions

diff --git a/src/renderer.c b/src/renderer.c
index 3c403a0..fb1647b 100644
--- a/src/renderer.c
+++ b/src/renderer.c
@@ -360,13 +360,21 @@ void r_xsection_destroy(r_xsection *xsection)
 }
 
 int r_xsection_update(r_window *rw, r_xsection *xsection,
-                      phy_field_info *fi, float *field,
+                      phy_field_info *fi, float *field, int64_t frame_index,
                       r_xsection_type type, float frac)
 {
 	size_t width, height, x, y, z;
 	uint8_t *pixels;
 	int pitch;
 
+	if (xsection->frame_index &&
+	    xsection->frame_index == frame_index &&
+	    xsection->last_frac == frac &&
+	    xsection->last_type == type)
+		return 0; // nothing's changed
+
+	printf("r_xsection_update: tick %ld\n", frame_index);
+
 	switch (type) {
 	case XSECTION_XY:
 		width = fi->width;
@@ -462,6 +470,9 @@ int r_xsection_update(r_window *rw, r_xsection *xsection,
 
 	xsection->aspect_ratio = (float)width / height;
 
+	xsection->last_frac = frac;
+	xsection->last_type = type;
+	xsection->frame_index = frame_index;
 	return 0;
 }