hi

currently I am developing a game in python called TankWar, it is basically 1vs1 game style and each player has its own turn. Both players control their respective tanks using the control keys and WASD and they can specify the missile's angle, velocity, tank position. I am using an equation to find the range of the missile and that works fine. The problem I am having is to design the projectile motion in parabola.

I know what the equation is but the missile is launched about 100 px above of the tank and I can't figure out why. Here's my code( sorry if you can't understand some parts ) i'll clarify if needed :)

```
# Designed by Georgi Christov ( a.k.a 8masterofpuppets8 )
# Last modified: 16.10.2009
from Tkinter import *
import time
import math
root = Tk(); root.geometry( "800x550+230+100" ); root.title( "TankCombat ( TM )" )
c = Canvas( root, width = 800, height = 400, bg = "white" ); c.pack()
# Variables and objects...
yGround = 350
border = c.create_rectangle( 3, 3, 797, 400, width = 2 )
ground = c.create_line( 0, yGround, 800, yGround )
x1, y1 = 150, yGround - 15
tank_1 = c.create_rectangle( 0, 0, 0, 0 )
tank1Cannon = c.create_line( 0, 0, 0, 0 ); angle1 = 30; missile1 = c.create_oval( 0, 0, 0, 0 )
initialSpeed = 70
############################################################################################################################################################
# Find the coordinates of a point given the angle, the length of the line and the starting coordinates
def end_x( x, d, a ):
return x + math.sin( math.radians( a ) ) * d
def end_y( y, d, a ):
return y - math.cos( math.radians( a ) ) * d
# Find the y position of the projectile given the x position, the angle, and the speed
def find_y( x, a, s ):
first = x * math.tan( math.radians( a ) )
second = ( 10 * ( x**2 ) / ( 2 * ( s**2 ) ) ) * ( 1 + ( math.tan( math.radians( a ) )**2 ) )
return first - second
############################################################################################################################################################
def launchMissile( xpos, ypos, angle, speed ):
global missile1
rangeOfMotion = ( ( speed ** 2 ) / 10 ) * math.sin( math.radians( 2 * angle ) ) # This is the range of motion
height = ( 1.0 / 20 ) * ( speed**2 ) * math.sin( math.radians( angle ) )**2 # Not sure if I need this
xInc = xpos
while xInc < xpos + rangeOfMotion:
time.sleep( 0.04 )
c.delete( missile1 )
missile1 = c.create_oval( xInc, ypos - find_y( xInc, angle, speed ), xInc + 5, ypos - find_y( xInc, angle, speed ) + 5, fill = "black" )
xInc += 5
c.update()
def keyboard( event ):
global x1, y1, angle1, initialSpeed
if event.keysym == "Left":
x1 -= 1
elif event.keysym == "Right":
x1 += 1
elif event.keysym == "Up":
if angle1 > 15:
angle1 -= 1
elif event.keysym == "Down":
if angle1 < 85:
angle1 += 1
elif event.keysym == "space":
launchMissile( x1, y1, 85 - angle1, initialSpeed )
root.unbind( "<Any-KeyPress>" )
tankCombat()
def tankCombat():
global yGround, tank_1, x1, y1, tank1Cannon, angle1, langle1
langle1.place_forget(); langle1 = Label( root, text = "Current angle >> " + str( angle1 ) ); langle1.place( relx = 1, x = -780, y = 440 )
c.delete( tank_1, tank1Cannon )
tank_1 = c.create_rectangle( x1, y1, x1 + 30, y1 + 15, fill = "green" )
tank1Cannon = c.create_line( x1 + 15, y1 + 7, end_x( x1 + 15, 15, angle1 ), end_y( y1 + 7, 15, angle1 ), width = 2 )
l1 = Label( root, text = "<< Player One Details >>", font = "Arial" ); l1.place( relx = 1, x = -750, y = 405 )
langle1 = Label( root, text = "Current angle >> " + str( angle1 ) ); langle1.place( relx = 1, x = -780, y = 440 )
tankCombat()
root.bind( "<Any-KeyPress>", keyboard )
mainloop()
```

This is until I figure out the proper algorithm after that I will add the second player and the other stuff :) all I need is a hint of what I am doing wrong... thx in advance!

*Edited 7 Years Ago by masterofpuppets*: n/a