catchyid Posted August 20, 2016 Share Posted August 20, 2016 Hi, What is really that controls the agent velocity in crowd simulation? I am confused because looking at the geometry spreadsheet in the simulation network, I see three attributes: velocity v, force and steer force. My questions: 1) is velocity read only? meaning, velocity is the result of applying forces, so in theory it should not be set manually? if not, then what does it mean to set velocity and set force on a particle? which one takes precedence velocity or force? Is this a kinematic or dynamic simulation? 2) how to force an agent to stop/freeze, i.e. still plays its clip but not moving in any direction? I used pop drag and set air resistance to a big number, e.g. 100,000, but still they kept on moving. The only way I was able make it stand still is by setting "Gait Speed" on a state to zero, which makes me believe that "Gait Speed" is multiplier to the final velocity? 3) what is the difference between force and steer force? Thanks, Quote Link to comment Share on other sites More sharing options...
cwhite Posted August 20, 2016 Share Posted August 20, 2016 The gait speed controls how the clip is retimed based on the particle speed, but if Limit Particle Speed to Gait Speed Range is enabled it is also used to set speed limits on the agent's particle. The 'steerforce' and 'steerweight' attributes accumulate a weighted average of different forces, which the POP Steer Solver (inside the crowd solver) uses to set the 'force' attribute 1 Quote Link to comment Share on other sites More sharing options...
catchyid Posted August 21, 2016 Author Share Posted August 21, 2016 Hi, Sorry, I am not sure I understand the concept. -Does "gait speed" control how fast/slow the agent in-place animation clip plays? meaning, if it's 1.0 then the animation plays at normal speed, if it's 2.0 then it plays twice as fast? But you said it's based on the particle speed, so does that mean that the resultant animation clip speed is = particle speed (computed by houdini) x gait speed? -If "Limit particle speed to gait speed range" is enabled, then it "forces the particle speed to fall within the the range specified Gait Speed and Allowed Variance"! I understand that as if we are setting the absolute max speed of the particle as = gait speed + variance m/s? so, if "gait speed" = 1.0 and variation = 0.0 then the maximum particle speed would be 1.0 m/s? -So if we use forces to control the particle/agent velocity, does that mean we should NOT change the value of the particle velocity vector manually? Sorry for long list of question hope you can help... Quote Link to comment Share on other sites More sharing options...
cwhite Posted August 21, 2016 Share Posted August 21, 2016 - For an in-place animation clip, the gait speed indicates how fast the agent was moving in the animation clip (think of it like the speed of a treadmill that the agent is on). The clip speed can then be adjusted based on the ratio between the particle speed and the gait speed to speed up or slow down the clip accordingly and avoid foot sliding. - If the speed limits are enabled, the min speed is (1 - variance/100) * gait speed, and the max speed is (1 + variance / 100) * gait speed 1 Quote Link to comment Share on other sites More sharing options...
catchyid Posted August 22, 2016 Author Share Posted August 22, 2016 Hi CWhite, thank very much for your reply... I am still confused - "think of it (gait speed) like the speed of a treadmill that the agent is on)": this sounds to me like describing "Clip Speed Multiplier", because if I increase the speed of a treadmill then the agent will just run faster in place, SO it's similar to the definition of "Clip Speed Multiplier" ? Actually, when I change the "Clip Speed Multiplier" I see noticable different in the agent clip playback, but when I change "gait speed" I don't notice any thing (pls, see next point for more details) - What makes more confused is that I only see the effect of "gait speed" when I check "Limit Particle Speed to Gait Speed Range", i.e. if's checked then the agent speed is controlled as you described in your previous post, HOWEVER if it's unchecked, then it seems like "gait speed" has no effect? e.g. I can set it to 1000 and agent still move with the same speed, i.e. only applied steering force affect them? Thanks CWhite for your time and patience Quote Link to comment Share on other sites More sharing options...
catchyid Posted August 23, 2016 Author Share Posted August 23, 2016 I've tested for some time, and I think I got it Quote Link to comment Share on other sites More sharing options...
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