Impl. color blending and unit test, minor API change

Signed-off-by: pacien <pacien.trangirard@pacien.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/blender/blender.c b/src/blender/blender.c
new file mode 100644
index 0000000..0e0835d
--- /dev/null
+++ b/src/blender/blender.c
@@ -0,0 +1,15 @@
+#include "blender/blender.h"
+#include <assert.h>
+#include <math.h>
+
+static ColorComponent blend_components(ColorComponent origin, ColorComponent target, TimeVector frame) {
+  return (ColorComponent) sqrt((TIME_UNIT - frame) * pow(origin, 2) + frame * pow(target, 2));
+}
+
+Color blender_blend_colors(Color origin, Color target, TimeVector frame) {
+  assert(frame >= TIME_ORIGIN && frame <= TIME_UNIT);
+  return (Color) {{blend_components(origin.rgba.r, target.rgba.r, frame),
+                   blend_components(origin.rgba.g, target.rgba.g, frame),
+                   blend_components(origin.rgba.b, target.rgba.b, frame),
+                   blend_components(origin.rgba.a, target.rgba.a, frame)}};
+}