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    MSPhysics tests and questions

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    • robintR Offline
      robint
      last edited by

      @faust07 said:

      Hi Robint
      Put this script into your baseplate (copy the 3 lines, select the plate, open MSP UI, select "Script", paste the lines into the Script window, run MSP):

      onTouch { |toucher, position, normal|
      MSPhysics::Simulation.reset
      }

      and the simulation stops "onTouch".

      Hi Faust, thanx for the tip, but not quite there yeet

      the simulation resets and I lose all the time/frame data at the bottom of screen - which is what I need for this to be useful.

      I tried .pause and .stop but they dont exist

      Is there something else I could try?

      As one door closes another one slams in your face

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      • robintR Offline
        robint
        last edited by

        Hi Faust

        Through the Ruby Code editor, I found a start_timer and stop_timer function

        Would this help?

        Say put start at the top to activate when staring sim,

        then stop_timer after the reset action line

        then display timer?

        sorry my newbie attempts at script (do you hav any recommendations on the best way to learn script for MSP - there's so much flack out there its hard to know where to start)

        Cheers

        Robin

        As one door closes another one slams in your face

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        • F Offline
          faust07
          last edited by

          Hi Robin,
          have tested to find a solution to pause simulation per script, but have nothing found until now.
          I'm a script newbie too. For my purposes I look into scripts of models from the experts at 3D-Warehouse (AntonS & PituPhysics) or ask them in Anton's main MSP post.

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          • robintR Offline
            robint
            last edited by

            Well we are both struggling, blind leading the blind

            FYI this timer thing is fundamental to simulating physical systems (mass speed acceleration)

            The on touch is a good start, just need to time the sequence and display result on reset

            opens up a whole new way of simulating mechanical systems

            as fundamental say as a thermometer is to tell you the temperature - if you see my point

            so I must perservere. If I get a result I will post it you

            Cheers

            Robin

            As one door closes another one slams in your face

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            • robintR Offline
              robint
              last edited by

              A bing moment has occured β˜€

              when I # out the reset line, I just had a ontouch line only and it outputs to screen what might be some sort of final velocity m/s on impact (according to the script info)

              pls see model

              Now I cant yet correlate that to the calc velocity which should be 14m/s on impact from 10m
              it comes out at 58 and varies with the UI sim setting of Newton update rate (currently 10)

              also from dropping from 5m gives 33 (should be 9.9m/s and is 1/sqr2 - .707) whereas 33/58 is ca.57

              maybe some dynamic friction in play?

              Is this a worthwhile line of enquiry?

              Cheers

              Robin

              ps the ball is in anton's examples funny little thing - and something for gamers pool table maybe?


              falling block.skp

              As one door closes another one slams in your face

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              • A Offline
                Anton_S
                last edited by

                Yes, the final velocity should be 14 m/s, and it is 14 m/s.

                Your script in the model you posted, just outputs the frame:

                onTouch { |toucher, position, normal, force, speed|
                  simulation.log_line("onTouch #{frame}")
                }
                

                That explains why you get unrelated results.

                To output the final velocity, you should change the code to output the speed:

                onTouch { |toucher, position, normal, force, speed|
                  simulation.log_line("onTouch #{speed}")
                }
                

                And besides, setting the linear damping of the falling box to zero will make the final velocity even more right because this will eliminate the dissipative force.

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                • robintR Offline
                  robint
                  last edited by

                  Thank you so much Anton, I was just about to post an apology for a stoopid boy Pike moment (no smilie for Duh 😳 )

                  but I read the second line and it outputs frame to screen, what a numpty

                  You gave me some other scrip that outputs velocity, strange to note that the cube reaches a terminal velocity ca 2m/s ca halfway down - intriguing. Is there something in there that simulates viscosity?

                  onUpdate {

                  Get current velocity

                  cv = this.get_velocity

                  Output it in the note

                  note = sprintf("Velocity: (%.3f, %.3f, %.3f)", cv.x, cv.y, cv.z)
                  simulation.display_note(note)
                  }

                  Cheers

                  Robin

                  As one door closes another one slams in your face

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                  • A Offline
                    Anton_S
                    last edited by

                    Yes, the viscosity is simulated by the linear damping. To remove the linear damping, select the desired group, open MSPhysics UI, activate the Properties tab, and set Linear Damping to 0.00. This should alter the height of terminal velocity.

                    If you meant something else, like water or buoyancy, you can add a buoyancy plane by navigating to (Menu)Extensions->MSPhysics->Create Buoyancy Plane. Although the liquid is not simulated. It's just the buoyancy force that is applied.

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                    • robintR Offline
                      robint
                      last edited by

                      Hi Anton

                      Just when I thought you cracked it with speed, something strange happens

                      When dropping the block from 10m = ok = 14m/s as per calc (see model)

                      Move the block down to 5m => nonesense answer like 0.07... (should be 9.9m/s)

                      Yet move block to other elevations like 8.5m or 2.5m , seems to work ok (but I haven't checked the result against calcs (12.9, 7)

                      So I am completely stumped πŸ˜’

                      BTW sometimes the block appears to penetrate the baseplate and slowly return to zero, could this be the reason?

                      Thats ruined my day

                      Cheers

                      Robin


                      falling block2.skp

                      As one door closes another one slams in your face

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                      • robintR Offline
                        robint
                        last edited by

                        Maybe uncovered a nasty bug? Anton

                        Here's a suggestion from your speed indicator

                        onUpdate {

                        Get current velocity

                        cv = this.get_velocity

                        Output it in the note

                        note = sprintf("Velocity: (%.3f)", cv.z)
                        simulation.display_note(note)
                        }

                        When it runs, on collision it displays 0.00 as expected, the block has stopped but we lost the terminal velocity

                        Could we say put an IF loop in the output velocity to note, only iff velocity <say .5m/s, then it should go to zero when the block stops (assuming no bounce)

                        Just a thought, maybe a simpler approach? from a ruby newby

                        Cheers

                        Robin

                        As one door closes another one slams in your face

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                        • robintR Offline
                          robint
                          last edited by

                          Sorry, Im getting tired

                          I meant it should retain the highest last value in note when the block stops

                          Apologies

                          Robin

                          As one door closes another one slams in your face

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                          • A Offline
                            Anton_S
                            last edited by

                            It's all cool πŸ˜„

                            Here is the code for viewing maximum velocity.

                            onStart {
                              @max_vz = 0
                            }
                            
                            onUpdate {
                              v = this.get_velocity
                              if v.z.abs > @max_vz
                                @max_vz = v.z.abs
                                simulation.display_note(sprintf("Max Speed %.3f m/s", @max_vz))
                              end
                            }
                            

                            And yes, the speed indicator in onTouch may not always work right, which is the problem of the physics engine that my wrapper is using.

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                            • robintR Offline
                              robint
                              last edited by

                              Hi Anton

                              Installed your script, works a treat and pretty accurate 😎

                              However I have meddled and got stuck, I cant find a way to print another result on a new line, tried everything, puts, print (can't find sprintf in docs either)

                              As you see I want to print elapsed time as well and it works but overwrite the Max Speed result on the same line

                              I feel really dumb getting stuck on this trivial matter, pls help 😒

                              BTW would I be right in saying that MSP script is a subset of official Ruby 2.0 and some elements like puts and print (they dont do anything on screen or riase an error)are left out?

                              Cheers

                              Robin


                              falling block3.skp

                              As one door closes another one slams in your face

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                              • A Offline
                                Anton_S
                                last edited by

                                Here:

                                onStart {
                                  @max_vz = 0
                                }
                                
                                onUpdate {
                                  v = this.get_velocity
                                  if v.z.abs > @max_vz
                                    @max_vz = v.z.abs
                                    simulation.display_note(sprintf("Max Speed %.3f m/s\nElapsed Time; %.2f s", @max_vz, world.time))
                                  end
                                }
                                
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                                • robintR Offline
                                  robint
                                  last edited by

                                  Anton, ooh that is nice

                                  from little acorns, great oaks grow

                                  So now we have a timer as well

                                  Maybe add

                                  add the x.y.z distance travelled

                                  and then I can perhaps simulate a cannon firing a cannon ball at a target

                                  and with a bit of wind and air friction, elementary gunnery for the Napoleonic War

                                  I will of course present my models to you for the consideration of others in the interest of MSP

                                  Cheers, many thanks
                                  Robin


                                  falling block4.skp

                                  As one door closes another one slams in your face

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                                  • robintR Offline
                                    robint
                                    last edited by

                                    Hi Anton

                                    Just seen your Turret thingy, blown away by it
                                    30 pages of code - I might as well try and become a brain surgeon!

                                    Link Preview Image
                                    3D Warehouse

                                    3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

                                    favicon

                                    (3dwarehouse.sketchup.com)

                                    Very skilful

                                    Robin

                                    As one door closes another one slams in your face

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                                    • gillesG Offline
                                      gilles
                                      last edited by

                                      Just playing with basics,
                                      Screw-MSP.gif
                                      brought me to some questions:

                                      When you at the screws,
                                      -one is static mesh and is collision shape fits perfectly.

                                      • to achieve the same collision shape for the mobil oneI had to it with several components.

                                      Any reason the soft isn't able to calculate the same collision shape but not static?

                                      To make those movements running well I used a workaround.

                                      For rotation we have hinge, motor, servo.
                                      For translation we have slider, piston, why not a linear motor?
                                      For translation + rotation we have corkscrew, why not motor + linear motor , servo + piston, servo + linear motor , linear motor + piston?
                                      For curve we have curvy slider and curvy piston, why not a curvy motor and curvy piston?

                                      Nota bene: just curiosity here, no request.


                                      Vis MSPhysic.skp

                                      " c'est curieux chez les marins ce besoin de faire des phrases "

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                                      • robintR Offline
                                        robint
                                        last edited by

                                        At last

                                        Terminal velocity
                                        Time
                                        Distance

                                        Now the basis of my cannon project

                                        Anton has made a sophisticated urret thingy available on 3D warehouse/msphysics

                                        but I want to make a simpler model for a gunner with inputs for
                                        horiz angle
                                        Azimuth
                                        muzzle velocity
                                        Range (from a range finder measurement of a distant target placed at random)
                                        Air density (from Bar pres, RH and temp)
                                        Air friction ?

                                        output > distance landed from target (eg a forward spotter)

                                        Simplistic stuff for a Napoleonic gunnery officer

                                        Maybe a moving target next (eg tank)

                                        On the 7th day god made Robin


                                        falling block6.skp

                                        As one door closes another one slams in your face

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                                        • F Offline
                                          faust07
                                          last edited by

                                          Hi Anton, after extensive tests with the fairly complex ice stage model, I can report that everything works very well.
                                          I just had to reverse some curves and exchange the programmed Curvy Piston Joint for the Orca. The calculation of the transformed emitter objects seems to work more precisely.
                                          This costs a little more time for the simulation, but the viewport problems no longer occur.
                                          That's great! Thank you very much!
                                          I have extended the simulation around a rain with middle large hailstones and it works.
                                          And for the future the integration of the good old SketchyPhysics fracture/split function and a kind of soft or flexible surfaces would be great...
                                          πŸ‘


                                          NewYear-Test_07.gif


                                          frame_000196.jpg

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                                          • A Offline
                                            Anton_S
                                            last edited by

                                            Thanks for testing and verifying, Faust. Next feature would be to improve performance of export to Skindigo and Kerkythea. I think there is a way to reduce export redundancy. The fracture thingy would be implemented too.

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