shooting mechanism in hockey game?

[mapleleafs]

hey, i'm making this hockey game in turing, but i don't know how to make the players shoot the puck properly. here's the general framework that i have for shooting so far:

code:

Input.Keydown (chars) if chars ('buttonForShoot') and playerHasPuck = true then      loop            exit when puckCoordinateX >= maxx            puckCoorinateX += 5      end loop      playerHasPuck = false end if

If i were to use this code in my game, the puck would just go straight at the wall/boards. I need to know how to make the puck go directly at the net, regardless of the location of the player/puck carrier. help is appreciated, and i will put you in my credits if i actually finish making this game.

and by the way, my hockey game will be moving from left and right, not up and down like the old SNES games

[Tony]

well first of all, NO. You dont make it into the loop. The force is applied to the puck just once. So you set puck's velocity and let it fly.

As for the direction. Use your trig/pythag knowledge to solve the "puck triangle"

hypotinuse = puck's total velocity
angle = tangent Y/X

solve for X, Y components and those are the compound velocities that will lead the puck straight into the net.

[mapleleafs]

i kind of understand, but the thing is i don't know trig....
so maybe you can give me the quick and dirty lesson on trigonometry, if not, can give me a nice site to learn from, cuz i am confus

[Tony]

get your hands on a grade 10 math textbook and read the chapter.

[naoki]

Hmm, try something like About.com and see what they can offer

Basically the idea behind trig is finding a position on a circle. As you know, you can use the radius of the circle and draw a right angled triangle based on it. The height of the triangle is the sin portion and the base length is the cos.

By determining the angle of the applied force of the stick, you can calculate by how much should the puck move in increments

[@DRI@N]

You could try and make a function to calculate slope...but the problem is it will give you a real number

[guruguru]

I'll try here.

Lets say the horizontal distance between the puck and net is 15. And the vertical distance is 10.

code:

/   o          /      t |      /            | adjacent = 10  /                | ( ----------------|      opposite = 15

To find the angle between the puck and the net, use a trig funtion called tan(). To much to explain how it works, but you can 'give' it the adjacent and opposite side and it will return the angle from the puck to the net.

tan^-1 (15/10) = 56 degrees

Ah sorry I got to go. I'll be back in 45 mins to complete this lesson . Maybe someone else can tell you how to implement it.

[guruguru]

Ok to continue. Lets say you want the total movement value to be 5. Think of 56 degrees as the ration between the x and y velocity values. (56/60). So to find the x velocity:

56 = x
90 TOTAL_MOVEMENT

x = 56 * TOTAL_MOVEMENT / 90
x = 3.1

So for this, the x velocity will be 3.1 pixels / cycle.

Using the same principle, the y value would be:

y = (90-56) * TOTAL_MOVEMENT / 90
y = 1.9

The y velcoity is 1.9 pixels / cycle.


To tie everything together... lets say the horizontal distance is 15. The vertical is 10.

code:

const TOTAL_MOVEMENT := 5 const RADIUS := 5 var puckX, puckY : int var xVelocity, yVelocity : real var angle : real var horDistance : int var verDistance : int var netX, netY := 50 puckX := 200 puckY := 150 horDistance := puckX - netX verDistance := puckY - netY if verDistance = 0 then       % Test for divide by zero     angle := 0 else     angle := arctand (horDistance/verDistance) end if xVelocity := angle * TOTAL_MOVEMENT / 90 yVelocity := (90 - angle) * TOTAL_MOVEMENT / 90 loop           puckX -= round (xVelocity)      puckY -= round (yVelocity)      cls      Draw.Oval (netX, netY, RADIUS, RADIUS, blue)      Draw.FillOval (puckX, puckY, RADIUS, RADIUS, black)      delay(100) end loop

Thats the basics. And you can easily port this code so if the puck is below the net... or going in opposite directions...

Haha me so stupid ! Arctand duh...

EDIT: Fixed code so it actually works !

EDIT: Wow... I gotta fix this code better.