Tutorial: Simulated solar system using Motion Paths
This tutorial demonstrates how to make a simple solar system simulation using SWiSH Max4 and its motion path feature. This is a great animation for a science class, or any space oriented website.
Note that the simulation is very approximate as it represents planet orbits as circular (not elliptical) paths. The simulation currently only displays the 4 inner planets, Mercury, Venus, Earth and Mars but it is easy to add more planets.
The simulation is based on the following approximate data:
Step 1: Create the motion paths
Concentric circles are used to define the motion paths of the different planets.
Using the Ellipse tool, draw a circle (any size) on the stage. To draw a circle as opposed to an ellipse, hold the shift key down while dragging the circle. Use the Reshape panel to accurately set the position (225, 150) and size of the circle (58, 58). Note that 58 corresponds to the size of Mercury’s orbit in millions of km. If you use the padlock to lock the aspect ratio, you will only need to modify one of the width or height parameters.
In the Outline panel, right click on the shape and select Copy Object from the menu.
Right click on the stage and select Paste in Place. This will paste an identical copy of the object on top of the original.
Repeat this process until there are 4 shapes shown in the outline panel. Select the bottom most shape in the Outline panel and change the height and width to be 228 (size of Mars orbit). Repeat this process for the next higher shapes setting their size to 150 and 108.
Finally you should be left with 4 concentric circles.
Step 2: Add the planets
Using the Ellipse tool again, draw another circle on the stage – anywhere and any size will do.
Repeat the previous copy / paste in place sequence to duplicate the object 4 more times. (ie a total of 5 gradient circles.)
Step 3: Resize and Animate the 1st planet.
The top most shape will be made into Mercury. Using the Reshape panel, set the width and height to be 3.8. (Mercury diameter is .38 that of earth).
Set a suitable color in the Properties panel – I used #CC6600.
Right click on either of the selected shapes and select Convert | Convert Last Selected Shape to Motion Path. The following dialog should appear.
Set the ‘Reverse the path’ checkbox (conventional notation is to show planets orbiting in counter clockwise direction). And set the Velocity to 4.1. A value of 4.1 is used based on Mercury’s speed of 4.1 million km per day.
Ensure the Remove the path shape checkbox is set.
Pressing the play button should show dot rotate around the path.
Right click on the currently selected shape, and use Convert | Convert to Movie Clip. Answer yes to the question about grouping effects if you are asked. This step allows this shape to have animation independently of any other object.
Step 4: Repeat for the other planets
Select the next available shape in the Outline panel and repeat the procedure described in step 3.
Before applying the motion path, ensure that the cursor is positioned at frame 1 in the Timeline panel for the chosen shape. Failure to do this will cause the animation to start from a frame other than the first frame.
Resize the shape according to the chosen planets diameter. (Use 9.5 for Venus, 10 for Earth and 5.3 for Mars). Choose an appropriate color (I used #FFFFFF for Venus, #3333FF for Earth and #FF9900 for Mars).
When asigning the motion path, remember to reverse the direction and choose speeds of 3.0, 2.6 and 2.1 for Venus, Earth and Mars. These speeds are based on the data table above.
Step 5: Add the Sun
Resize the remaining shape to 20 and set its color to #FFFF00. Position it in the center (225,150). Note that the diameter of the sun is not to scale compared to the planet diameters.
Step 6: Set the background color and movie size
In the Outline panel, select Scene_1. In the Properties panel select Movie Properties…
Set the size of the movie to 450×300 and the background color to black.
The simulation file can be downloaded from here.
As stated above, this is a very crude simulation. It is intended more as a tutorial on motion paths rather than a real simulation. If you are interested in astronomy and planets, check out Celestia which is a free 3D sky map and space viewer / simulator.