gravity

ok I have my gravity equation, how would I go about putting this into speeds? (x and y speeds)...? Maybe the next step would be A = F/M? :confused:

'speed' is a scalar quantity (it is just a magnitude), what you are talking about is 'velocity', which is a vector quantity because it has both a magnitude and a direction. It's a minor technical point :)

Yes, I would suggest you go ahead with a = f/m.

ok im doing good, but I'm having trouble using the gravity constant, it's so small....that the computer reads it as 0...

const double grav = (6.7*pow(10,-11));

comes up as 0 when I test it in a messagebox
:(

ok can someone check my math? here's my algorithm:

Code:

---

//get x force
                                                //get radius
                                                xradius = body1.x-body2.x;
                                       
                                        xforce = grav*((body1.mass * body2.mass) / (xradius));
                                        xaccel = (xforce / body2.mass);
                                        body2.xspeed = body2.xspeed + xaccel;

                                        body2.x = body2.x + body2.xspeed;

                                        //get y force
                                                //get radius
                                                yradius = body1.y-body2.y;
                                       
                                        yforce = (grav * body1.mass * body2.mass) / (yradius);
                                        yaccel = (yforce / body2.mass);
                                        body2.yspeed = body2.yspeed + yaccel;

                                        body2.y = body2.y + body2.yspeed;
                                       


                                        SetMoons();

---

SetMoons() just draws the moons from the information in each class....

basically I get the force from the equation

F = constant * ((m1*m2)/radius²);
and then put that into A = MF

Accel = body1.mass * force;

and then added accel to the speed....I did this for X and Y....but it doesn't work right

anyone? :(

its not working....the "moon" goes all over the place...

I think your Force formula should be like this:
F = (constant * m1*m2)/radius2;

and you're also not squaring your radius in your code so it should be like:
xforce = (grav* body1.mass * body2.mass) / xradius2;
yforce = (grav * body1.mass * body2.mass) / yradius2;

:cool:

Good job! It looks really amazing!:cool:
BTW, I think there's a bug when closing the window. Perhaps you can stop your loop or timer for drawing when a WM_CLOSE or WM_DESTORY message is sent to your window?

Yeah sorry, while the animation (for loop) is going to make it able to be seen I put some sleep statements in there. Im not too good with animation.

BTW Without the sleep statement it looks really cool..I thnk I added that one into the zip too :cool:

You should create a background thread to do the drawing, else the app can only be closed with Ctrl+Alt+Del. Or use PeekMessage instead of GetMessage and use idle time for drawing.