This isn't a real physics engine, so it might not belong in this forum, but this is the closest I can think of regarding how it works.

Let's say for a minute that I have a ball. Not an ordinary ball - just a cylinder that's flat on top and on the bottom, but is round when you look at it from the top. It moves around in the level and can collide with other objects. When it collides, it bounces.

And it works great - on angles facing the right. For all the other angles, instead of bouncing off of the wall, the ball sticks to it! This is my code. I've tried everything humanly possible to fix it, but nothing works.

PS: I made a post earlier and got a reply saying that BOUNCE is an xyz, not a pan-tilt-roll. I've checked the manual and it is in fact an angle, not a position.

Code:

---

 function ball_event
{
	my_motion.x *= 0.5;
	my_motion.y *= 0.5;
	my_motion.z *= 0.5;
	if(bounce.pan < 90) && (bounce.pan > -90)
	{
		my_motion.x += cos(bounce.pan)*(vec_length(my_motion));
		my_motion.y += sin(bounce.pan)*(vec_length(my_motion));
	}
	else
	{
		my_motion.x -= cos(bounce.pan)*(vec_length(my_motion));
		my_motion.y -= sin(bounce.pan)*(vec_length(my_motion));
	}
}

action ball
{
	ball_object = my;
	my.event = ball_event;
	my.enable_block = on;
	my.enable_entity = on;
	var space_on;
	while(1)
	{
		proc_late();
		ball_pan1.pos_x = int(my.x) - 33;
		ball_pan1.pos_y = table_panel.pos_y + (2048 - int(my.y)) - 33;
		my_motion.z = 0;
		my_motion.y -= 0.25 * time;
		if(key_space) && (space_on == off)
		{
			space_on = on;
			my_motion.x -= 15 * time;
		}
		if(!key_space)
		{
			space_on = off;
		}
		c_move(my, nullvector, my_motion, ignore_passents+activate_trigger+use_aabb);
		if(my.x < 0){my.x = 0;}
		if(my.x > 1024){my.x = 1024;}
		if(my.y < 0){my.y = 0;}
		if(my.y > 2048){my.y = 2048;}
		wait(1);
	}
} 

---

BOUNCE IS an xyz-vector with a maximum of x/y/z= 1, as far as I know.
You could calculate angles first
vec_to_angle(temp, bounce);
and then
if(temp.pan < 90) && (temp.pan > -90)

Why didn't I think about that? Thanks, I'll give that a try.

Okay, I tried it out and... well, thanks, it does work better on some walls. However, it's still not entirely bug-proof... it's supposed to bounce at the correct angle and mainly slide along walls. Anyone know how this code could be improved?

Code:

---

function ball_event
{
	my_motion.x = -my_motion.x;
	my_motion.y = -my_motion.y;
	
	my_motion.x *= 0.5;
	my_motion.y *= 0.5;
	vec_to_angle(temp, bounce); 
	if(temp.pan > -1) && (temp.pan < 181)
	{
		my_motion.x += cos(temp.pan)*(vec_length(my_motion));
		my_motion.y -= sin(temp.pan)*(vec_length(my_motion));
	}
	else
	{
		my_motion.x -= cos(temp.pan)*(vec_length(my_motion));
		my_motion.y += sin(temp.pan)*(vec_length(my_motion));	
	}
}

action ball
{
	ball_object = my;
	my.event = ball_event;
	my.enable_block = on;
	my.enable_entity = on;
	var space_on;
	while(1)
	{
		proc_late();
		ball_pan1.pos_x = int(my.x) - 32;
		ball_pan1.pos_y = table_panel.pos_y + (2048 - int(my.y)) - 32;
		my_motion.z = 0;
		my_motion.y -= 0.25 * time;
		if(key_space) && (space_on == off)
		{
			space_on = on;
			my_motion.x -= 15 * time;
		}
		if(!key_space)
		{
			space_on = off;
		}
		c_move(my, nullvector, my_motion, ignore_passents+activate_trigger+use_aabb);
		if(my.x < 0){my.x = 0;}
		if(my.x > 1024){my.x = 1024;}
		if(my.y < 0){my.y = 0;}
		if(my.y > 2048){my.y = 2048;}
		my_motion.x += key_cur*0.5*time;
		my_motion.x -= key_cul*0.5*time;
		my_motion.y += key_cuu*0.5*time;
		my_motion.y -= key_cud*0.5*time;
		wait(1);
	}
}

---

I haven't tested this code:

var my_motion[3];
var my_bounce[3];
var bouncing;

function ball_event
{
bouncing=1;
vec_to_angle(my_bounce, bounce);
my_bounce.tilt=0;
my_bounce.roll=0;
}

action ball
//first part of code...
//calculate speed:
my_motion.x += (key_cur-key_cul)*0.5*time;
my_motion.y += (key_cuu-key_cud)*0.5*time;
my_motion.z=0;

//include bounce set in event function(rotate speed vector if bouncing)
if(bouncing==1){vec_rotate(my_motion,my_bounce);
bouncing=0;//instant reset

c_move(my, nullvector, my_motion, ignore_passents+activate_trigger+use_aabb);
my.x=clamp(my.x,0,1024); my.y=clamp(my.y,0,2048);
wait(1);
//rest of code