moved to relative float equivalence

tuples/Cargo.lock

@@ -1,5 +1,32 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "approx"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f2a05fd1bd10b2527e20a2cd32d8873d115b8b39fe219ee25f42a8aca6ba278"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
+[[package]]
+name = "num-traits"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "tuples"
 version = "0.1.0"
+dependencies = [
+ "approx",
+]

tuples/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+approx = "0.4"

tuples/src/lib.rs

@@ -1,4 +1,18 @@
+#[macro_use]
+extern crate approx;
+
+use std::f32;
+
 type PointVector = (f32, f32, f32, f32);
+type Dimensions = (f32, f32, f32);
+
+fn point(dims: Dimensions) -> PointVector {
+    (dims.0, dims.1, dims.2, 1.0)
+}
+
+fn vector(dims: Dimensions) -> PointVector {
+    (dims.0, dims.1, dims.2, 0.0)
+}
 
 fn tuple_x(tuple: PointVector) -> f32 {
     tuple.0
@@ -13,10 +27,10 @@ fn tuple_z(tuple: PointVector) -> f32 {
 }
 
 fn tuple_is_point(tuple: PointVector) -> bool {
-    tuple.3 == 1.0
+    relative_eq!(1.0, tuple.3)
 }
 fn tuple_is_vector(tuple: PointVector) -> bool {
-    tuple.3 == 0.0
+    relative_eq!(0.0, tuple.3)
 }
 
 #[cfg(test)]
@@ -27,21 +41,33 @@ mod tests {
     fn get_point() {
         let tuple = (4.3, -4.2, 3.1, 1.0);
 
-        assert_eq!( 4.3,  tuple_x(tuple));
-        assert_eq!(-4.2,  tuple_y(tuple));
-        assert_eq!( 3.1,  tuple_z(tuple));
+        assert_relative_eq!( 4.3,  tuple_x(tuple));
+        assert_relative_eq!(-4.2,  tuple_y(tuple));
+        assert_relative_eq!( 3.1,  tuple_z(tuple));
         assert_eq!(true,  tuple_is_point(tuple));
         assert_eq!(false, tuple_is_vector(tuple));
     }
 
+    #[test]
+    fn create_point() {
+        let point = point((4.0, -4.0, 3.0));
+        assert_eq!(true, tuple_is_point(point));
+    }
+
     #[test]
     fn get_vector() {
         let tuple = (4.3, -4.2, 3.1, 0.0);
 
-        assert_eq!( 4.3,  tuple_x(tuple));
-        assert_eq!(-4.2,  tuple_y(tuple));
-        assert_eq!( 3.1,  tuple_z(tuple));
+        assert_relative_eq!( 4.3,  tuple_x(tuple));
+        assert_relative_eq!(-4.2,  tuple_y(tuple));
+        assert_relative_eq!( 3.1,  tuple_z(tuple));
         assert_eq!(false, tuple_is_point(tuple));
         assert_eq!(true,  tuple_is_vector(tuple));
     }
+
+    #[test]
+    fn create_vector() {
+        let vector = vector((4.0, -4.0, 3.0));
+        assert_eq!(true, tuple_is_vector(vector));
+    }
 }