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  Rotating Particle (Flamethrower) Tower Spawn Acceleration  (Read 1001 times)
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Offline Slyth2727
« Posted 2013-04-10 23:33:49 »

Right, in my Java2d TD Game I have set on making a tower that has 3 barrels which spin around and, using my particle engine, spew out fire particles at the direction the barrels are pointing. I have no trouble with the rotation, and I can set the acceleration vector by saying particle.setAcc(X, Y). If the Y value is positive, the particle will go down by that many pixels per tick. Negative, opposite. Same thing for X, just on the X axis. My only problem is if I have the rotation method going like this:

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            if (rotateT >= rotateS) {
               rotation++;
               rotateT = 0;
            } else {
               rotateT++;
            }


and my method for spawning in particles is this:

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            Screen.addOverParticle(X, Y, velocityx, velocityy, size, amount, life, image);


how would I get it so it the spawning of the particles spins around in a circle as if a flamethrower is turning around in a continuous circle, firing. I have a few ideas, but I think it will be very CPU intensive the ways I am thinking. Thanks -cMp

Was I before Chuang Tzu who dreamt about being a butterfly, or am I now a butterfly who dreams about being Chuang Tzu?
Offline relminator
« Reply #1 - Posted 2013-04-11 00:46:45 »

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float ang = (float)Math.toRadians(rotation);
velocityx = (float)Math.cos(ang) * speed;
velocityy = (float)Math.sin(ang) * speed;


Offline Slyth2727
« Reply #2 - Posted 2013-04-11 01:02:08 »

I get an interesting effect with this. The particles spawn like a box and the width gets bigger than smaller while the height gets smaller than bigger in an indirect variation, if you will. Not the effect I was looking for and still am Wink but a nice one..

Was I before Chuang Tzu who dreamt about being a butterfly, or am I now a butterfly who dreams about being Chuang Tzu?
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Offline StumpyStrust
« Reply #3 - Posted 2013-04-11 02:02:18 »

If you get a box it is because you are using different speeds for x and y.

If you want it so it looks like someone with a water hose spinning in a circle with flames instead of water, then what relminator said is right. You might be doing something different in your particle system.

Here is how my emitters do this

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float temp = angle2 - angle1; 
         
         float newAngle = (float) (((Rnd.randomPlus(temp))+angle1) * Math.PI/180);
         newAngle *= -1;
         if(randomV)
         {
            float v = Rnd.randomPlus(vel);
            x.setVel((float)(v*FastMath.cos(newAngle)),(float) (v*FastMath.sin(newAngle)));
         }
         else
         {
            x.setVel((float)(vel*FastMath.cos(newAngle)),(float) (vel*FastMath.sin(newAngle)));
         }

Note in this I have extra options like random vel and emitting particles between 2 angles but the key is the x.setVel

Offline Slyth2727
« Reply #4 - Posted 2013-04-11 23:33:05 »

Ok I see now! Works like a charm, thank you very much Smiley

Was I before Chuang Tzu who dreamt about being a butterfly, or am I now a butterfly who dreams about being Chuang Tzu?
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