[camera] lerping and miscelanious

include/camera.h

@@ -6,7 +6,7 @@
 typedef struct Camera
 {
 	Vec position;
-	Vec *follow; /* the target position to lerp on */
+	Vec *target; /* the target position to lerp on */
 	float speed; /* camera lerp speed with 0 < speed <= 1 */
 } Camera;
 

include/vec.h

@@ -8,7 +8,7 @@ typedef struct Vec
 } Vec;
 
 /* like memcpy but for vectors */
-void vec_cpy(Vec *destination, Vec *source);
+void vec_cpy(Vec *destination, Vec source);
 
 /* apply a force on a vector */
 void vec_add(Vec *vector, Vec force);
@@ -22,4 +22,8 @@ void vec_mul(Vec *vector, float scale);
 /* divise a vector by a scale */
 void vec_div(Vec *vector, float scale);
 
+/* Linear interpolation between two vectors.
+ * Require a scale ranging from 0 to 1 (0 is instant, 1 is completly still). */
+void vec_lerp(Vec *from, Vec to, float scale);
+
 #endif /* _DEF_VEC */

src/camera.c

@@ -1,5 +1,7 @@
 #include "camera.h"
+#include "vec.h"
 
 void camera_step(Camera *camera)
 {
+	vec_lerp(&camera->position, *camera->target, camera->speed);
 }

src/main.c

@@ -26,9 +26,9 @@ int main(void)
 
 	/* create camera */
 	Camera camera = {
-		.follow = &player.position
+		.target = &player.position
 	};
-	vec_cpy(&camera.position, &player.position);
+	vec_cpy(&camera.position, player.position);
 
 	/* main game loop */
 	step_event(&player, &level, &camera);

src/vec.c

@@ -1,9 +1,9 @@
 #include "vec.h"
 
-void vec_cpy(Vec *destination, Vec *source)
+void vec_cpy(Vec *destination, Vec source)
 {
-	destination->x = source->x;
-	destination->y = source->y;
+	destination->x = source.x;
+	destination->y = source.y;
 }
 
 void vec_add(Vec *vector, Vec force)
@@ -29,3 +29,12 @@ void vec_div(Vec *vector, float scale)
 	vector->x /= scale;
 	vector->y /= scale;
 }
+
+void vec_lerp(Vec *from, Vec to, float scale)
+{
+	Vec temp = {};
+	vec_cpy(&temp, to);
+	vec_sub(&temp, *from);
+	vec_mul(&temp, scale);
+	vec_add(from, temp);
+}