Add more color functions

src/raylib.h

@@ -1357,6 +1357,8 @@ RLAPI Color ColorFromNormalized(Vector4 normalized);                        // G
 RLAPI Vector3 ColorToHSV(Color color);                                      // Get HSV values for a Color, hue [0..360], saturation/value [0..1]
 RLAPI Color ColorFromHSV(float hue, float saturation, float value);         // Get a Color from HSV values, hue [0..360], saturation/value [0..1]
 RLAPI Color ColorTint(Color color, Color tint);                             // Get color multiplied with another color
+RLAPI Color ColorInvert(Color color);                                       // Get color inverted
+RLAPI Color ColorGrayscale(Color color);                                    // Get color grayscaled
 RLAPI Color ColorBrightness(Color color, float factor);                     // Get color with brightness correction, brightness factor goes from -1.0f to 1.0f
 RLAPI Color ColorContrast(Color color, float contrast);                     // Get color with contrast correction, contrast values between -1.0f and 1.0f
 RLAPI Color ColorAlpha(Color color, float alpha);                           // Get color with alpha applied, alpha goes from 0.0f to 1.0f

src/rtextures.c

@@ -4432,6 +4432,29 @@ Color ColorTint(Color color, Color tint)
     return result;
 }
 
+// Get color inverted
+Color ColorInvert(Color color)
+{
+    Color result = color;
+
+    color.r = 255 - color.r;
+    color.g = 255 - color.g;
+    color.b = 255 - color.b;
+
+    return result;
+}
+
+// Get color grayscaled
+Color ColorGrayscale(Color color)
+{
+    Color result = color;
+
+    Vector4 normalizedColor = ColorNormalize(color);
+    *((unsigned char *)&result) = (unsigned char)((normalizedColor.x*0.299f + normalizedColor.y*0.587f + normalizedColor.z*0.114f)*255.0f);
+
+    return result;
+}
+
 // Get color with brightness correction, brightness factor goes from -1.0f to 1.0f
 Color ColorBrightness(Color color, float factor)
 {