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Course: Pixar in a Box>Unit 4

Lesson 2: Code your own simulation

Multiple spring-mass system

Mass spring systems are essential for simulations in animation. By adding a second spring and mass, you can create more complex models like hair, trees, and clothing. Different spring values mimic various materials, making mass spring systems versatile for designing realistic animations. Explore and create your own simulations for endless possibilities!

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• In the video (from 48 second) it is stated that to calculate force for spring1 we need take into account additionally spring2 force and spring2 damping force but I don't see such components in later video equation.
Did I miss something?
• At , we learn that the spring and damping forces for the lower spring must be applied to mass 1, which makes sense. But the code, at , does not include the second spring in the calculation of the net force of mass 1.

Am I misunderstanding or is that an error in the video?

Also, if you were to include the force from the lower spring upon mass 1 as well as mass 2, aren't you somehow double-counting that? Don't you have to apportion the total spring force to the individual masses in order to conserve energy?
• For the first part, I think, yes, these things are not added in the code. We also do not get a realistic feeling when the simulation runs in the video.

For the second part, no we are not double counting the forces. The spring applies equal force on both of its sides. You can think of it trying to do whatever it can to get back to its natural length, so it applies equal forces on both of them.

The effect of these forces, however depends on other factors like individual masses and stiffness of the spring.
(1 vote)
• are you guys like students from around the world or what?
• i watched this vidio twice, and all i heard was springs, x, y, even more springs. it does not make scence to me.
• its kinda difficult for the coding.
(1 vote)
• At , why does she say "ow" instead of "now"?
(1 vote)
• What kind of other spring mass?