How do i make my dragon my dragon circle a specific blockpos?

TheRPGAdventurer · November 26, 2018

This question is more java mathematics related rather than minecraft related, so i plan to make a dragon whistle item that would command a dragon to either fly towards or circle the player when flying, so is my code for making the dragon circle the player and flying correct?

    protected boolean tryToCircleBlockPos(BlockPos midPoint, double speed) { // midpoint is gonna be player position
    	dragon.setFlying(true);
		return dragon.getNavigator().tryMoveToXYZ(midPoint.getX() + 0.5 * Math.PI, midPoint.getY() + 10, midPoint.getZ() + 0.5 * Math.PI, speed);
    	
    }

Animefan8888 · November 26, 2018

2 hours ago, TheRPGAdventurer said:

so is my code for making the dragon circle the player and flying correct?

Does the dragon circle the player? And it doesnt look correct to me you are not doing any trigonometry.

Cadiboo · November 26, 2018

You might want to google “draw circle with points”. I found a stackoverflow answer with a similar search that was very helpful and described how to find points for both an elipse and a circle

Edited November 27, 2018 by Cadiboo

TheRPGAdventurer · November 27, 2018

yes circle above the player

V0idWa1k3r · November 27, 2018

Well, you could store the player's position somewhere within the dragon/AI in addition to the angle variable.

When the AI to circle around kicks in calculate the current angle between these vectors [dragonPos - playerPos], [unitZ](<- I am not sure which direction the game consideres forward, I think it's unitZ though). You can calculate an angle between two vectors using

arccos((vec1 DOT vec2) / (vec1.length * vec2.length))

if I am not mistaken.

Then you can start circling, You know the angle the dragon started at so now you can just add to it each tick. The amount you add should be manually tweaked based on your dragon's speed.

Now you have a new angle, which is your previous angle + X. You can then use this angle to calculate the position the dragon needs to be at:

[x = playerX + r * cos(a), y = playerY + NUM, z = playerZ + r * sin(a)

Where r is the distance from the dragon to the player you want to acheive(radius of your circle) and NUM is the height of the dragon relative to the player.

Then just tell the dragon to move there.

Edited November 27, 2018 by V0idWa1k3r

TheRPGAdventurer · November 27, 2018

Just now, V0idWa1k3r said:
Well, you could store the player's position somewhere within the dragon/AI in addition to the angle variable.

When the AI to circle around kicks in calculate the current angle between these vectors [dragonPos - playerPos], [unitZ](<- I am not sure which direction the game consideres forward, I think it's unitZ though). You can calculate an angle between two vectors using
arccos((vec1 DOT vec2) / (vec1.length * vec2.length))

what does DOT mean

TheRPGAdventurer · November 27, 2018

also would it be good to use this instead of arccos?

dragon.getDistanceSq(midPoint);

V0idWa1k3r · November 27, 2018

32 minutes ago, TheRPGAdventurer said:

what does DOT mean

A dot product of two vectors.

23 minutes ago, TheRPGAdventurer said:

also would it be good to use this instead of arccos?

arccos is the operation that is the reverse of the cos operation. The squared distance is just x*x + y*y + z*z. So the answer is no since these are completely different operations.

TheRPGAdventurer · November 27, 2018

where is arccos found? Math.class? or MathHelper.class

Animefan8888 · November 27, 2018

29 minutes ago, TheRPGAdventurer said:

where is arccos found? Math.class? or MathHelper.class

Should be in Math, but it might be called acost instead of arccos.

TheRPGAdventurer · November 28, 2018

	protected boolean tryToCircleBlockPos(BlockPos midPoint, double speed) {   	
    	Vec3d vec1 = new Vec3d(midPoint.getX(),midPoint.getY(),midPoint.getZ());
    	Vec3d vec2 = dragon.getPositionVector();
    	double r = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector() ) );
        double x = midPoint.getX() + r * Math.cos(dragon.rotationYaw + 90);
    	double y = midPoint.getY() + 50;
    	double z = midPoint.getZ() + r * Math.sin(dragon.rotationYaw + 90);
	    return dragon.getNavigator().tryMoveToXYZ(midPoint.getX() + x, midPoint.getY() + y, midPoint.getZ() + z, speed);
    	
    }

so how'sthis

V0idWa1k3r · November 28, 2018

5 minutes ago, TheRPGAdventurer said:

Vec3d vec1 = new Vec3d(midPoint.getX(),midPoint.getY(),midPoint.getZ());

Vec3d vec2 = dragon.getPositionVector();

Did I tell you "Get the position of the dragon and the position of the center and do things with those vectors"? No, I told you to

On 11/27/2018 at 7:06 AM, V0idWa1k3r said:

calculate the current angle between these vectors [dragonPos - playerPos], [unitZ]

And you did none of that. Moving on

6 minutes ago, TheRPGAdventurer said:

double r = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector() ) );

Did I tell you "Oh, the radius of the circle is the angle you calculate"? No, because that makes zero sense. I told you

On 11/27/2018 at 7:06 AM, V0idWa1k3r said:

When the AI to circle around kicks in calculate the current angle between these vectors

On 11/27/2018 at 7:06 AM, V0idWa1k3r said:

Then you can start circling, You know the angle the dragon started at so now you can just add to it each tick.

Moving on

7 minutes ago, TheRPGAdventurer said:

double x = midPoint.getX() + r * Math.cos(dragon.rotationYaw + 90);

Did I tell you "Use the dragon's rotation yaw plus an arbitrary number as an angle"? No, because unless you are rotating your dragon that makes no sense(and if you are - it is always looking away from the player and moves sideways). I told you to

On 11/27/2018 at 7:06 AM, V0idWa1k3r said:

Now you have a new angle, which is your previous angle + X. You can then use this angle to calculate the position the dragon needs to be at

Moving on:

9 minutes ago, TheRPGAdventurer said:

return dragon.getNavigator().tryMoveToXYZ(midPoint.getX() + x, midPoint.getY() + y, midPoint.getZ() + z, speed);

So you have 2 vectors - midPoint and your [x, y, z]. [x, y, z] is midPoint + someNumbers. If you add them together you are essentially doubling the midPoint vector(kinda). So if your dragon is at [200, 100, 200] you are telling it to move to ~[400, 250, 400]. I don't think that it is what you want and that is not what I told you.

TheRPGAdventurer · November 28, 2018

also what is this "a" for

playerX + r * cos(a)

Cadiboo · November 28, 2018

1 hour ago, TheRPGAdventurer said:
also what is this "a" for
playerX + r * cos(a)

If r is radius then I assume a is angle

TheRPGAdventurer · November 28, 2018

	protected boolean tryToCircleBlockPos(BlockPos midPoint, double speed) {   	
    	Vec3d vec1 = new Vec3d(midPoint.getX(),midPoint.getY(),midPoint.getZ());
    	Vec3d vec2 = dragon.getPositionVector();
    	double a = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector()));
    	Vec3d r = vec1.subtract(vec2); 
        double x = midPoint.getX() + r.x * Math.cos(a);
    	double y = midPoint.getY() + 50;
    	double z = midPoint.getZ() + r.z * Math.sin(a);
        return dragon.getNavigator().tryMoveToXYZ(midPoint.getX() + x, midPoint.getY() + y, midPoint.getZ() + z, speed);  	
    	     
	}

V0idWa1k3r · November 28, 2018

1 hour ago, TheRPGAdventurer said:

Vec3d vec1 = new Vec3d(midPoint.getX(),midPoint.getY(),midPoint.getZ());

Vec3d vec2 = dragon.getPositionVector();

6 hours ago, V0idWa1k3r said:

calculate the current angle between these vectors [dragonPos - playerPos], [unitZ]

You are still not doing that.

1 hour ago, TheRPGAdventurer said:

double x = midPoint.getX() + r.x * Math.cos(a);

On 11/27/2018 at 7:06 AM, V0idWa1k3r said:

r is the distance from the dragon to the player you want to acheive(radius of your circle)

Where did you get the impression that radius is somehow a vector?

1 hour ago, TheRPGAdventurer said:

return dragon.getNavigator().tryMoveToXYZ(midPoint.getX() + x, midPoint.getY() + y, midPoint.getZ() + z, speed);

6 hours ago, V0idWa1k3r said:

So you have 2 vectors - midPoint and your [x, y, z]. [x, y, z] is midPoint + someNumbers. If you add them together you are essentially doubling the midPoint vector(kinda). So if your dragon is at [200, 100, 200] you are telling it to move to ~[400, 250, 400]. I don't think that it is what you want and that is not what I told you.

TheRPGAdventurer · November 28, 2018

	protected boolean tryToCircleBlockPos(BlockPos midPoint, double speed) {   	
    	Vec3d vec1 = new Vec3d(midPoint.getX(),midPoint.getY(),midPoint.getZ());
    	Vec3d vec2 = dragon.getPositionVector(); // "calculate the angle between these 2 vectors" I think this im missing and im bad a t trigonometry
    	
    	double a = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector()));
    	double r = dragon.getDistanceSqToCenter(midPoint);  // radius is now a double
        double x = midPoint.getX() + r * Math.cos(a); // x = playerX + r * cos(a) as stated
    	double y = midPoint.getY() + 50; // y = playerY + NUM as stated
    	double z = midPoint.getZ() + r  * Math.sin(a); //  z = playerZ + r * sin(a) as stated
        return dragon.getNavigator().tryMoveToXYZ(x, y, z, speed);  	// no more adding
    	     
	}

V0idWa1k3r · November 28, 2018

Well, the only thing that you are missing right now is

On 11/27/2018 at 7:06 AM, V0idWa1k3r said:

these vectors [dragonPos - playerPos], [unitZ]

What I am saying is vec1 is [dragonPos - playerPos] and vec2 is [unitZ]. This

2 hours ago, TheRPGAdventurer said:

double a = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector()));

Is the line that calculates the angle, you just need to get the vec1 and vec2 right.

Also this

2 hours ago, TheRPGAdventurer said:

double r = dragon.getDistanceSqToCenter(midPoint);

is a squared distance, as the name of the method implies. Have your radius be a constant or something, this will make your dragon fly away from the player at an exponential rate.

Edited November 28, 2018 by V0idWa1k3r

TheRPGAdventurer · November 29, 2018

what does unitZ mean?

Edited November 29, 2018 by TheRPGAdventurer
d

TheRPGAdventurer · November 29, 2018

what does unitZ mean?

TheRPGAdventurer · November 29, 2018

protected boolean tryToCircleBlockPos(BlockPos midPoint, double speed) {       
        Vec3d vec1 = dragon.getPositionVector().subtract(midPoint.getX(),midPoint.getY(),midPoint.getZ());
        Vec3d vec2 = dragon.getPositionVector(); // what does unitZ mean
        
        double a = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector()));
        double r = 12;  // radius is now a constant 
    //    double r = dragon.getDistance(midPoint.getX(),midPoint.getY(),midPoint.getZ()); can i use dis?
        double x = midPoint.getX() + r * Math.cos(a); // x = playerX + r * cos(a) as stated
        double y = midPoint.getY() + 20; // y = playerY + NUM as stated
        double z = midPoint.getZ() + r * Math.sin(a); //  z = playerZ + r * sin(a) as stated
        return dragon.getNavigator().tryMoveToXYZ(x + 0.5, y + 0.5, z + 0.5, speed);      // no more adding
             
    }

V0idWa1k3r · November 29, 2018

4 hours ago, TheRPGAdventurer said:

what does unitZ mean?

[0, 0, 1]. But I don't atually know what direction the game considers the forward one, so it might be some other unit vector.

TheRPGAdventurer · November 29, 2018

its z of course, in models z is forward or back ward, by [0,0,1] you mean; new Vec3d(0,0,1) or new BlockPos(0,0,1)

V0idWa1k3r · November 29, 2018

1 hour ago, TheRPGAdventurer said:

new Vec3d(0,0,1) or new BlockPos(0,0,1)

The only difference between these two is that the first one uses doubles while the second one uses ints. You need the double one.

1 hour ago, TheRPGAdventurer said:

its z of course, in models z is forward or back ward

It should be, but I wouldn't count on that.

TheRPGAdventurer · November 29, 2018

	protected boolean tryToCircleBlockPos(BlockPos midPoint, double speed) {   	
    	Vec3d vec1 = dragon.getPositionVector().subtract(midPoint.getX(),midPoint.getY(),midPoint.getZ());
    	Vec3d vec2 = new Vec3d(0,0,1); // "calculate the angle between these 2 vectors" I hope vec3d is compat with Blockpos Vec3i
    	
    	double a = Math.acos((vec1.dotProduct(vec2)) / (vec1.lengthVector() * vec2.lengthVector()));
    	double r = 12;  // radius is now a constant 
        double x = midPoint.getX() + r * Math.cos(a); // x = playerX + r * cos(a) as stated
    	double y = midPoint.getY() + 20; // y = playerY + NUM as stated
    	double z = midPoint.getZ() + r * Math.sin(a); //  z = playerZ + r * sin(a) as stated
        return dragon.getNavigator().tryMoveToXYZ(x + 0.5, y + 0.5, z + 0.5, speed);  	// no more adding    	     
	}

they do go to me, but they dont rotate on a position, am i doing something wrong, does this needs to be a static or a loop?

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How do i make my dragon my dragon circle a specific blockpos?

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