New basics gets the remainder of the stuff from old basics

EPSILON, MAX_DISTANCE, NearZeor, NearlyEqual, TooFar.

src/basics/basics.hh

@@ -9,10 +9,66 @@
 #ifndef __BASICS_BASICS_HH__
 #define __BASICS_BASICS_HH__
 
+#include <cmath>
+
 #include "basics/color.hh"
 #include "basics/matrix.hh"
 #include "basics/ray.hh"
 #include "basics/types.hh"
 #include "basics/vector.hh"
 
+
+/**
+ * A very small constant. If a value is between EPSILON and 0.0, it is
+ * considered to be zero.
+ */
+const Double EPSILON = 1.0e-10;
+
+/**
+ * The maximum distance a ray can travel. This is the maximum value t can be.
+ */
+const Double MAX_DISTANCE = 1.0e7;
+
+/**
+ * Determine if the value is "close enough" to zero. Takes the absolute value
+ * and compares it to `EPSILON`.
+ *
+ * @see EPSILON
+ *
+ * @param [in] value    The value to check
+ * @returns `true` if the value is close enough to zero
+ */
+template <typename T>
+inline bool
+NearZero(const T value)
+{
+    return std::fabs(value) < EPSILON;
+}
+
+
+/**
+ * Determine if two values are "close enough" to be considered equal. Subtracts
+ * one from the other and checks if the result is near zero.
+ *
+ * @see NearZero
+ *
+ * @param [in] left     The left parameter
+ * @param [in] right    The right parameter
+ * @returns `true` if the values are close enough to be equal
+ */
+template <typename T>
+inline bool
+NearlyEqual(const T left,
+            const T right)
+{
+    return NearZero(left - right);
+}
+
+
+inline bool
+TooFar(const Double& value)
+{
+    return value > MAX_DISTANCE;
+}
+
 #endif /* __BASICS_BASICS_HH__ */