Add feature to evaluate FlatScene at multiple frame values.

Reduced the number of function parameters by grouping attributes
together into camera and transform.

Filter out the bundles and cameras to correctly calculate the
world matrices needed.

Support bundle reprojection for multiple cameras in one scene
evaluation.

Issue #114.

src/mmscenegraph/rust/src/attr/mod.rs

@@ -36,6 +36,28 @@ pub enum AttrId {
     None,
 }
 
+#[derive(Debug, Clone, Hash, Eq, PartialEq, Ord, PartialOrd)]
+pub struct AttrTransformIds {
+    pub tx: AttrId,
+    pub ty: AttrId,
+    pub tz: AttrId,
+    //
+    pub rx: AttrId,
+    pub ry: AttrId,
+    pub rz: AttrId,
+    //
+    pub sx: AttrId,
+    pub sy: AttrId,
+    pub sz: AttrId,
+}
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq, Ord, PartialOrd)]
+pub struct AttrCameraIds {
+    pub sensor_width: AttrId,
+    pub sensor_height: AttrId,
+    pub focal_length: AttrId,
+}
+
 #[derive(Debug, Clone, Default)]
 pub struct AttrDataBlock {
     pub static_attrs: Vec<StaticAttr>,