assume variable player is the pointer to the player entity ...
... if you move the code in the players action you can replace "player" by "my"


#define CAM_DISTANCE 200 		// distance to player
VECTOR v;				// helper variable for vector

vec_set(camera.x,player.x);		// camera on players position
vec_set(camera.pan,player.pan);		// look same direction as player
vec_for_angle(v, camera.pan);		// get the vector for the direction
vec_normalize(v,CAM_DISTANCE);		// set lenght of vector to distance of camera to player
vec_sub(camera.x,v);			// subtract vector from camera position (= move backwards)

vec_set( camera.x, vector(-100,0,50) ); // change this number to move camera relative to player
vec_rotate( camera.x, player.pan );
vec_add( camera.x, player.x );
vec_set( camera.pan, player.pan );

if (key_space) 
{
me.z +=16; //if space is pressed jump
ent_animate(me,"jump",jump_percentage,ANM_CYCLE);
//ent_playsound(me,woosh,100); //jumping plays woosh sound
}
if (me.z > 52) 
{
c_move(me,vector(0,0,-4.7),nullvector,GLIDE); //if the player is above z.20 then glide down at 0.8 speed, enable collision
//ent_animate(me,"jump",jump_percentage,ANM_CYCLE);
}