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engine/3d/src/Color1uint8.hpp

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+/**
+  @file Color1uint8.h
+
+  @maintainer Morgan McGuire, graphics3d.com
+
+  @created 2007-01-30
+  @edited  2007-01-30
+
+  Copyright 2000-2007, Morgan McGuire.
+  All rights reserved.
+ */
+
+#ifndef G3D_COLOR1UINT8_H
+#define G3D_COLOR1UINT8_H
+
+#include "platform.hpp"
+#include "g3dmath.hpp"
+
+namespace G3D
+{
+
+/**
+ Represents a Color1 as a packed integer.  Convenient
+ for creating unsigned int vertex arrays.
+
+ <B>WARNING</B>: Integer color formats are different than
+ integer vertex formats.  The color channels are automatically
+ scaled by 255 (because OpenGL automatically scales integer
+ colors back by this factor).  So Color3(1,1,1) == Color3uint8(255,255,255)
+ but Vector3(1,1,1) == Vector3int16(1,1,1).
+
+ <B>Note</B>:
+ Conversion of a float32 to uint8 is accomplished by min(iFloor(f * 256)) and
+ back to float32 by u / 255.0f.  This gives equal size intervals.
+Consider a number line from 0 to 1 and a corresponding one from 0 to 255.  If we use iRound(x * 255), then the mapping for three critical intervals
+are:
+
+<pre>
+let s = 0.5/255
+  float             int       size
+[0, s)           -> 0          s
+[s, s * 3)       -> 1         2*s
+(1 - s, 1]       -> 255        s
+</pre>
+
+If we use max(floor(x * 256), 255), then we get:
+
+<pre>
+let s = 1/256
+  float             int           size
+[0, s)           -> 0               s
+[s, 2 * s)       -> 1               s
+(1 - s, 1]       -> 255             s
+</PRE>
+and the intervals are all the same size, thus giving equal precision to all values.
+ */
+G3D_BEGIN_PACKED_CLASS(1)
+class Color1uint8
+{
+private:
+    // Hidden operators
+    bool operator<(const Color1uint8&) const;
+    bool operator>(const Color1uint8&) const;
+    bool operator<=(const Color1uint8&) const;
+    bool operator>=(const Color1uint8&) const;
+
+public:
+    uint8 value;
+
+    Color1uint8()
+        : value(0)
+    {
+    }
+
+    explicit Color1uint8(const uint8 _v)
+        : value(_v)
+    {
+    }
+
+    Color1uint8(const class Color1& c);
+
+    inline bool operator==(const Color1uint8& other) const
+    {
+        return value == other.value;
+    }
+
+    inline bool operator!=(const Color1uint8& other) const
+    {
+        return value != other.value;
+    }
+
+} G3D_END_PACKED_CLASS(1)
+} // namespace G3D
+#endif