Impl. color blending and unit test, minor API change

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

3 files changed, 37 insertions, 1 deletions

diff --git a/include/blender/color.h b/include/blender/color.h
index cdf488a..22ed563 100644
--- a/include/blender/color.h
+++ b/include/blender/color.h
@@ -20,7 +20,10 @@ typedef uint8_t ColorComponent;
  * Compatible with the libMLV representation.
  */
 typedef union {
-  ColorComponent r, g, b, a;
+  struct {
+    ColorComponent r, g, b, a;
+  } rgba;
+
   MLV_Color mlv;
 } Color;
 
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)}};
+}
diff --git a/test/blender/blender.c b/test/blender/blender.c
new file mode 100644
index 0000000..7c33198
--- /dev/null
+++ b/test/blender/blender.c
@@ -0,0 +1,18 @@
+#include "blender/blender.h"
+#include <assert.h>
+
+static void test_color_blending() {
+  Color a = {{0xFF, 0xED, 0x00, 0x00}};
+  Color b = {{0x00, 0x47, 0xAB, 0x00}};
+  Color result = blender_blend_colors(a, b, 0.125);
+
+  assert(result.rgba.r == 0xEE &&
+         result.rgba.g == 0xDF &&
+         result.rgba.b == 0x3C &&
+         result.rgba.a == 0x00);
+}
+
+int main(int argc, char **argv) {
+  test_color_blending();
+  return 0;
+}