Initial godot setup with billboarding experiment.

shaders/billboard.gdshader

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+shader_type spatial;
+
+void vertex() {
+    vec3 right = normalize(cross(vec3(0.0, 1.0, 0.0), to_camera));
+    vec3 up = vec3(0.0, 1.0, 0.0);
+    vec3 forward = normalize(cross(right, up));
+    mat4 billboard_matrix = mat4(
+        vec4(right, 0.0),
+        vec4(up, 0.0),
+        vec4(forward, 0.0),
+        vec4(model_pos, 1.0)
+    );
+    MODELVIEW_MATRIX = VIEW_MATRIX * billboard_matrix;
+}

shaders/billboard.gdshader.uid

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+uid://du6owhb1rw1ic