[SOLVED] Calculating angle to mouse

Game Mechanics
#1

I need help calculating the angle to the mouse from entities,

if(orders.get(0) instanceof MoveOrder){
        		MoveOrder mo = (MoveOrder)orders.get(0);
        		double xd = mo.x - x;
        		double yd = mo.y - y;
        		double rotation = Math.toDegrees(Math.atan2(yd,xd))+270;
        		rot = rotation;
        		System.out.println(rot);
        		orders.remove(0);
        	}

This is my current code, but it doesn’t seem to work, and the movement code is:

while(rot > 360)rot-= 360;
		while(rot < 0)rot+= 360;
		double movementAngle = Math.toRadians(rot);
        x += Math.sin(movementAngle) * 0.5;
        y += Math.cos(movementAngle) * 0.5;

can anyone help?

#2

everything you have looks correct to me. I assume it’s messing up at the stage of getting the angle from the mouse, right? make sure you’re getting the right positions in your MoveOrder and entity position.

#3

Can you be more specific in “doesn’t work”?

#4

this should help:
angle = Math.toDegrees(Math.atan2(MouseY - entity.y, MouseX - entity.x));

#5

It seems to go in completely random directions, and doesn’t move to the mouse at all…

#6

to move: (Worked in my game. see Walking sprites in show case)
x += delta * Math.sin(Math.toRadians(entity.angle));
y += delta * Math.cos(Math.toRadians(entity.angle));

#7

you need to find out where you are going wrong. are you getting the correct angle from your first segment?

#8

Okay, i’ve done some testing, and it seems to work fine x Axis, but messes up somewhere on the y Axis, as in, if i tell it to go from (0,0) to (10,0) it works fine, if i want to move just in the x Axis it has to be

MoveOrder mo = (MoveOrder)orders.get(0);
        		double xd = mo.x - x;
        		double yd = mo.y - y;
        		double rotation = Math.toDegrees(Math.atan2(yd,xd))+90;

However, if i want to move in the y Axis it has to be

MoveOrder mo = (MoveOrder)orders.get(0);
        		double xd = mo.x - x;
        		double yd = mo.y - y;
        		double rotation = Math.toDegrees(Math.atan2(yd,xd))+270;

Which even further confuses me…

I’ve got it to move in the right direction by doing it like this

double movementAngleX = Math.toRadians(rot);
		double movementAngleY = Math.toRadians(rot+180);
        x += Math.sin(movementAngleX) * 0.5;
        y += Math.cos(movementAngleY) * 0.5;
        if(orders.size() > 0){
        	if(orders.get(0) instanceof MoveOrder){
        		MoveOrder mo = (MoveOrder)orders.get(0);
        		double xd = mo.x - x;
        		double yd = mo.y - y;
        		double rotation = Math.toDegrees(Math.atan2(yd,xd))+90;
        		rot = rotation;
        		System.out.println(rot);
        		orders.remove(0);
        	}
        }

But then the rotation on the image is messed up, the rendering code is (im using LWJGL)

        
        GL11.glTranslated(x+32, y+32, 0);
        GL11.glRotated(rot, 0, 0, -1);
        GL11.glBegin(GL11.GL_QUADS);
        GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex2f(-32, -32);
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex2f(32, -32);
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex2f(32, 32);
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex2f(-32, 32); 
        GL11.glEnd();

Anyone got any ideas?

#9

i have made a mistake
this is y coord code:
y -= delta * Math.cos(Math.toRadians(entity.angle));

and try GL11.Rotatef with

angle = angle % 360.0f;
GL11.Rotatef((float)angle…)

#10

Thanks! Got it to work,

double movementAngle = Math.toRadians(rot);
        x += Math.sin(movementAngle) * 0.5;
        y -= Math.cos(movementAngle) * 0.5;
        if(orders.size() > 0){
        	if(orders.get(0) instanceof MoveOrder){
        		MoveOrder mo = (MoveOrder)orders.get(0);
        		double xd = mo.x - x;
        		double yd = mo.y - y;
        		double rotation = Math.toDegrees(Math.atan2(yd,xd))+90;
        		rot = rotation;
        		orders.remove(0);
        	}
        }


        float angle = (float) (rot % 360.0f);
        GL11.glRotated(angle+180.0f, 0, 0, 1);
#11

glRotate() can handle angles outside 360 degrees, but you should keep the actual stored rotation (rot) to 0-360 degrees.