http://www.opserver.de/wiki/index.php/Improved_Player_Movement

///////////////////////////////
#include <acknex.h>
#include <default.c>
#include <mtlFX.c>

#define STATE skill1
#define ANIMATION skill2
///////////////////////////////

function main()
{
	//video_screen = 1;
	detail_size = 2;
	level_load("templatetest.WMB");
	wait(2);
}

function camera_follow(ENTITY* ent)
{
	while(1) 
	{
		vec_set(camera.x,vector(-150,10,50));  // camera position relative to the player      
		vec_rotate(camera.x,ent.pan); // rotate the camera position with the player
		vec_add(camera.x,ent.x);      // add player position
		vec_set(camera.pan,vector(ent.pan,-13,0)); // look in player direction, slighty down      
		wait(1);
	}
}

action player_move()
{
	camera_follow(me);
	
	if(key_cuu ==0 | key_cud ==0 | key_cul ==0 | key_cur ==0 | key_ins ==0 | key_ctrl ==0 | key_space ==0)
	{my.STATE = 1;}
	
	//Parameter
	var movespeed = 10;
	var turnspeed = 10;
	var fallacc = 3.68;
	var jumpacc = 20;
	
	//Temporary
	VECTOR movedir;
	vec_set(movedir, vector(0, 0, 0));
	ANGLE rotdir;
	vec_set(rotdir, vector(0, 0, 0));
	var grounddist;
	
	//determine player height
	c_setminmax(my);
	wait(1);
	var feedheight = -my.min_z;
	
	//adjust bounding box
	my.min_x *= 0.4;
	my.min_y *= 0.8;
	my.min_z = 0;
	my.max_x *= 0.4;
	my.max_y *= 0.8;
	my.max_z *= 0.8;
	
	proc_mode = PROC_EARLY;

	while(1)
	{
		//define key inputs
		movedir.x = key_cuu-key_cud; //*(1+key_shift*2); FORWARD-BACKWARD
		movedir.y = key_ctrl-key_ins; // STRAFE LEFT-RIGHT
			                         
		//calculate speed
		movedir.x *= movespeed*time_step;
		movedir.y *= movespeed*time_step;		

		my.pan += (key_cul-key_cur)*5*time_step;  // TURN/ROTATE LEFT-RIGHT
		
		c_move(my,vector(movedir.x, movedir.y, 0), nullvector, GLIDE|IGNORE_PASSABLE);
		if(key_cuu | key_cud)
		{
			my.STATE = 2;
		}
		if(key_ins | key_ctrl)
		{
			my.STATE = 3;
		}
		if(key_cuu & key_ctrl | key_cuu & key_ins)
		{
			my.STATE = 2;
		}
		if(key_cud & key_ctrl | key_cud & key_ins)
		{
			my.STATE = 2;
		}
		
		//check distance to ground
		grounddist = c_trace(my.x, vector(my.x, my.y, my.z-10000), IGNORE_ME|IGNORE_PASSABLE)-feedheight;
		if(grounddist > 0 || movedir.z < 0)
		{
			//gravity acceleration
			movedir.z += fallacc*time_step;
		}else
		{
			movedir.z = 0;
		}
		
		//apply gravity
		my.z -= minv(movedir.z*time_step, grounddist);
		
		if(grounddist-minv(movedir.z*time_step, grounddist) == 0)
		{
			//jump
			if(key_space)
			{
				my.STATE = 4;
			}

		}
	
		if(my.STATE == 1)
		{
			var stand_percentage;
			ent_animate(my,"stand",stand_percentage, ANM_CYCLE);
			stand_percentage += 2 * time_step;

		}
		
		if(my.STATE == 2)
		{
			my.ANIMATION += 1*movedir.x;
			ent_animate(my,"walk",my.ANIMATION,ANM_CYCLE);
			if(!key_cuu | !key_cud | !key_cul | !key_cur | !key_ins | !key_ctrl | !key_space)
			{my.STATE = 1;}
		}
		
		if(my.STATE == 3)
		{
			my.ANIMATION += 1*movedir.y;
			ent_animate(my,"walk",my.ANIMATION,ANM_CYCLE);
			if(!key_cuu | !key_cud | !key_cul | !key_cur | !key_ins | !key_ctrl | !key_space)
			{my.STATE = 1;}
		}
		
		if(my.STATE == 4)
		{
			var jump_percentage = 0;
			while(jump_percentage < 100)
			{
				movedir.z = -jumpacc;
				ent_animate(my,"jump",jump_percentage,0);
				jump_percentage += 10*time_step;
				wait(1);
			}
			if(!key_space)
			{
				my.STATE = 1;
			}
		}
		
	wait(1);	
	}

}