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Angles and Trajectory

calclavia

By calclavia
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calclavia World Shaper

calclavia

Posted
Posted

This is more of a math question than a modding question. It is for my ICBM mod and I can't really figure it out.

 

I am given point A and B. A missile is to be shot from point A to B. What would the trajectory (rotationPitch) of the missile be in angles? Also, what direction (rotationYaw) will the missile shoot in angles?

 

I tried using Tangent but it didn't really work properly. I looked at the EntityArrow class as a reference but they already had the rotationYaw and rotationPitch as known variables (they get the variables from the entity player's rotation).

 

LaunchYaw will be the direction of the missile the missile being shot. LaunchPitch will be the trajectory of the missile.

this.setLocationAndAngles(position.x, position.y, position.z, launchYaw, launchPitch);

 

I am guessing the solution would be related to sine cosine, tangent functions. Since I know the two points, I know the distance between the two points.

 

AngleQuestion.png

width=409 height=100http://calclavia.com/uploads/banner.png[/img]
starwolfminecrafter Tree Puncher

starwolfminecrafter

Posted
Posted

having done some quick research anything luanched into suborbit is at roughly a 78 degree angle, looking at some pictures of test missle impacts the return angle is about 45 degrees-90 degrees

 

suborbit is about 160–2,000 km (100–1,240 miles) above the Earth's surface

the entre speed and reentry speed is about  7 km/s(entry) 4km/s (reentry)

hope this helps

calclavia World Shaper

calclavia

Posted
  • Author
Posted
  On 5/19/2012 at 1:27 PM, starwolfminecrafter said:

having done some quick research anything luanched into suborbit is at roughly a 78 degree angle, looking at some pictures of test missle impacts the return angle is about 45 degrees-90 degrees

 

suborbit is about 160–2,000 km (100–1,240 miles) above the Earth's surface

the entre speed and reentry speed is about  7 km/s(entry) 4km/s (reentry)

hope this helps

 

Sorry but that's not what I was looking for. I posted a image of what I'm trying to get above.

width=409 height=100http://calclavia.com/uploads/banner.png[/img]
Jarofdoom Creeper Killer

Jarofdoom

Posted
Posted

You want the bearing of the rocket? If so, that's equivalent to tan-1(distance between source and where you put the angle 0 text on that image/distance between target and source).

 

See this image: 500px-TrigonometryTriangle.svg.png

 

Point B is your destination, point A is your source and point C is required to work out the length of line b,  which goes into the tan function.

calclavia World Shaper

calclavia

Posted
  • Author
Posted
  On 5/19/2012 at 1:41 PM, Jarofdoom said:

You want the bearing of the rocket? If so, that's equivalent to tan-1(distance between source and where you put the angle 0 text on that image/distance between target and source).

 

See this image: 500px-TrigonometryTriangle.svg.png

 

Point B is your destination, point A is your source and point C is required to work out the length of line b,  which goes into the tan function.

Yes, I want to find the bearing of the rocket.

 

Good solution, but I do not know the point C and also the line B. How would I calculate to find that? Point C is required in order for me to use tangent.

width=409 height=100http://calclavia.com/uploads/banner.png[/img]
Jarofdoom Creeper Killer

Jarofdoom

Posted
Posted

Point C is simply the point where your lines intersect at right angles

on the 0-degree line. Therefore point C has the same X value as A and same Y as B. For an example calculation, let point A be of co-ordinate (1,2) and point B be co-ordinate (4,5) This means point C has co-ordinates (1,5). Next, we get line b and c. b=sqrt((4-1)^2+(5-2)^2)=4.24264069 c=sqrt((1-1)^2+(5-2)^2)=3 . Next, we plug this into Tan^-1 to get Angle=Tan^-1(3/4.24264069)=35.26 degrees, or 0.6154797 radians.

calclavia World Shaper

calclavia

Posted
  • Author
Posted
  On 5/19/2012 at 2:22 PM, Jarofdoom said:

This is all GCSE-level trigononmetry, BTW.

 

Sorry, but I am only in junior high school. :) If I am not as good as you in math, I will not be surprised. But anyway, thanks for the reply. I feel stupid I didn't thought of that solution. I was trying to think too hard when it's something really simple. Thanks.

width=409 height=100http://calclavia.com/uploads/banner.png[/img]
CowedOffACliff Tree Puncher

CowedOffACliff

Posted
Posted
  On 5/19/2012 at 2:57 PM, Jarofdoom said:

  Quote

  Quote

This is all GCSE-level trigononmetry, BTW.

 

Sorry, I just got in high school. :)

 

You'll be a couple steps ahead then :P

 

I would argue that you can't really make assumptions based on age/education.

 

In my high school you learn basic trig in geometry, and then real trig is entirely optional.

I accidentally the everything then NullPointerException.

Jarofdoom Creeper Killer

Jarofdoom

Posted
Posted
  On 5/19/2012 at 5:57 PM, CowedOffACliff said:

  Quote

  Quote

  Quote

This is all GCSE-level trigononmetry, BTW.

 

Sorry, I just got in high school. :)

 

You'll be a couple steps ahead then :P

 

I would argue that you can't really make assumptions based on age/education.

 

In my high school you learn basic trig in geometry, and then real trig is entirely optional.

 

No assumptions were made. What are you on about? SoHCaHToA *is* basic trig...

atrain99 World Shaper

atrain99

Posted
Posted
  On 5/19/2012 at 2:55 PM, calclavia said:

  Quote

This is all GCSE-level trigononmetry, BTW.

 

Sorry, but I am only in junior high school. :) If I am not as good as you in math, I will not be surprised. But anyway, thanks for the reply. I feel stupid I didn't thought of that solution. I was trying to think too hard when it's something really simple. Thanks.

Wow... Glad to find a kindred spirit!    :D

So, what would happen if I did push that shiny red button over there? ... Really? ... Can I try it? ... Damn.

atrain99 World Shaper

atrain99

Posted
Posted
  On 5/20/2012 at 10:12 PM, atrain99 said:

  Quote

  Quote

This is all GCSE-level trigononmetry, BTW.

 

Sorry, but I am only in junior high school. :) If I am not as good as you in math, I will not be surprised. But anyway, thanks for the reply. I feel stupid I didn't thought of that solution. I was trying to think too hard when it's something really simple. Thanks.

Wow... Glad to find a kindred spirit!    :D

You need to take gravity into account here. A missile usually goes into suborbit, but if you are just firing it over a *short* distance, then you should be able to make a parabolic path... I have no idea how to do it (Algebra II is not helping here), but google knows...  :P

So, what would happen if I did push that shiny red button over there? ... Really? ... Can I try it? ... Damn.

atrain99 World Shaper

atrain99

Posted
Posted
  On 5/20/2012 at 10:59 PM, calclavia said:

I figured out a solution for my problem but the result is completely different from this. I simply used the atan2() java function to get the radians and convert it into a angle.

That works! Glad you solved your problem!

So, what would happen if I did push that shiny red button over there? ... Really? ... Can I try it? ... Damn.

Jarofdoom Creeper Killer

Jarofdoom

Posted
Posted
  On 5/20/2012 at 10:59 PM, calclavia said:

I figured out a solution for my problem but the result is completely different from this. I simply used the atan2() java function to get the radians and convert it into a angle.

 

The answer is not completely different. atan = tan^-1

atrain99 World Shaper

atrain99

Posted
Posted
  On 5/21/2012 at 12:03 AM, calclavia said:

I haven't learn this in school yet. But can you please tell me the difference between atan and atan2 functions in Java? Atan2 seems to work an atan does not work.

Just play around with the console. The atan function may be using radians as it's primary in/out, so a value above 2pi may not work or be wonked out.

So, what would happen if I did push that shiny red button over there? ... Really? ... Can I try it? ... Damn.

Jarofdoom Creeper Killer

Jarofdoom

Posted
Posted
  On 5/21/2012 at 12:26 AM, atrain99 said:

  Quote

I haven't learn this in school yet. But can you please tell me the difference between atan and atan2 functions in Java? Atan2 seems to work an atan does not work.

Just play around with the console. The atan function may be using radians as it's primary in/out, so a value above 2pi may not work or be wonked out.

 

This, but also see http://docs.oracle.com/javase/6/docs/api/java/lang/Math.html#atan2%28double,%20double%29

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