add 2d module: camera, frame animation, tweens

1 files changed, 31 insertions, 0 deletions

diff --git a/kon/kon2d.h b/kon/kon2d.h
index fce4bb2..badaed0 100644
--- a/kon/kon2d.h
+++ b/kon/kon2d.h
@@ -72,4 +72,35 @@ int kon_animDone(const kon_anim_t *anim);
 /* draws frame index of a sheet of frameWidth by frameHeight frames with its top left at x, y */
 void kon_drawFrame(kon_framebuffer_t *fb, const kon_image *sheet, int frameWidth, int frameHeight, int index, int x, int y, int flip);
 
+/*** tweens ***/
+
+typedef enum kon_ease {
+	KON_EASE_LINEAR,
+	KON_EASE_IN, /* starts slow */
+	KON_EASE_OUT, /* ends slow */
+	KON_EASE_INOUT
+} kon_ease_t;
+
+/* a number that glides from one value to another. start one with kon_tweenStart, feed it time with kon_tweenStep and read it with
+   kon_tweenValue. a tween that was never started just holds 0, kon_tweenSet gives it a value to hold */
+typedef struct kon_tween {
+	float from, to;
+	float duration, time;
+	kon_ease_t ease;
+} kon_tween_t;
+
+/* t from 0 to 1, out of range is clamped */
+float kon_easeValue(kon_ease_t ease, float t);
+
+void kon_tweenSet(kon_tween_t *tween, float value);
+void kon_tweenStart(kon_tween_t *tween, float from, float to, float seconds, kon_ease_t ease);
+
+/* glides from wherever it is now, so it can be redirected in the middle of a move */
+void kon_tweenTo(kon_tween_t *tween, float to, float seconds, kon_ease_t ease);
+
+/* returns the new value */
+float kon_tweenStep(kon_tween_t *tween, float dt);
+float kon_tweenValue(const kon_tween_t *tween);
+int kon_tweenDone(const kon_tween_t *tween);
+
 #endif