From 7371831f317d86bd41173f31ee4cb86f7c4d551a Mon Sep 17 00:00:00 2001
From: chavlin <chris.havlin@gmail.com>
Date: Wed, 11 Dec 2024 11:08:25 -0500
Subject: [PATCH] add camera.set_position

---
 .gitignore                         | 3 ++-
 examples/amr_osmesa.py             | 4 ++++
 yt_idv/cameras/trackball_camera.py | 4 ++++
 yt_idv/tests/test_yt_idv.py        | 9 +++++++++
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index 19283ec1..5532662c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -111,8 +111,9 @@ ENV/
 .vscode/
 .idea/
 
-# Screenshots
+# Screenshots and examples
 snap_*.png
+examples/*.png
 
 # pytest outputs
 report.html
diff --git a/examples/amr_osmesa.py b/examples/amr_osmesa.py
index 3be5a775..c01a44a3 100644
--- a/examples/amr_osmesa.py
+++ b/examples/amr_osmesa.py
@@ -15,3 +15,7 @@
 
 image = rc.run()
 yt.write_bitmap(image, "step2.png")
+
+rc.scene.camera.set_position([1.0, 1.5, 3.0])
+image = rc.run()
+yt.write_bitmap(image, "step3_set_position.png")
diff --git a/yt_idv/cameras/trackball_camera.py b/yt_idv/cameras/trackball_camera.py
index aae1d1ff..f4fd10a3 100644
--- a/yt_idv/cameras/trackball_camera.py
+++ b/yt_idv/cameras/trackball_camera.py
@@ -86,3 +86,7 @@ def offset_position(self, dpos=None):
 
     def _compute_matrices(self):
         pass
+
+    def set_position(self, pos):
+        self.position = pos
+        self._update_matrices()
diff --git a/yt_idv/tests/test_yt_idv.py b/yt_idv/tests/test_yt_idv.py
index 144cd3e6..07f68e59 100644
--- a/yt_idv/tests/test_yt_idv.py
+++ b/yt_idv/tests/test_yt_idv.py
@@ -62,6 +62,15 @@ def test_snapshots(osmesa_fake_amr, image_store):
     image_store(osmesa_fake_amr)
 
 
+def test_camera_position(osmesa_fake_amr, image_store):
+    """Check that we can update the camera position"""
+    vm = osmesa_fake_amr.scene.camera.view_matrix
+    osmesa_fake_amr.scene.camera.set_position([0.5, 2.0, 3.0])
+    # check that the view matrix has changed
+    assert np.sum(np.abs(vm - osmesa_fake_amr.scene.camera.view_matrix)) > 0.0
+    image_store(osmesa_fake_amr)
+
+
 def test_depth_buffer_toggle(osmesa_fake_amr, image_store):
     osmesa_fake_amr.scene.components[0].use_db = True
     image_store(osmesa_fake_amr)