i attach my hip file

the case:
1/ so i have a flat grid, then trying to grow particle from outside (edge of the grid) then slowly walk-in' (move) to the center area .it's not the particle that i want to move , but i want the point/location where the particle is birthing from. so the particle just static, but the growing process is moving slowly from edge to center.

i'm not an experienced user so based on what i learn so far ,i try to use blendshape,point,scatter to achieve this kind of effect. But doesn't look good. coz the blend shape is a blend, so the growing effect is dissolving rather than moving as u can see (it's noticeable specially for wide area). so to make it moving smoothly i have to create some more paint SOP to add more detail/steps in movement.

so i need help, there might be another better way to create this effect.

2/ other case, how about if i want to animate the brush stroke (no need to use blendshape)
so it can resample the stroke to some duration, so automatically ‘draw’ the stroke as we play the animation.(kind like ‘autopaint’ in discreet flame/inferno).

3/ what if i want to use an external image file (ex: contain the animation of brush stroke created with external app.) to control the grow of the particle. so rather than using paint and blendshape, i just use maybe shader SOP. than apply a texture/animation file. Then how to transfer this color/shader information to point level (Cd)? is it possible? is there any other way i can get closer to this goal.

i need some advise,

thanx

For (1), try a Creep SOP. The idea would be to creep your emitter geometry across (within) a fixed grid.

For (3), you can use an external image to control aspects of your particles by bringing it into COPs, then referencing it with the pic() function. Type ‘exhelp pic’ in the textport to see how to use it.

I'm not sure about animating brush strokes (in Paint or Edit, I assume you mean) - the whole point of those nodes is to allow you to do work by hand. If you want to animate changes in your model, well, that's what the procedural workflow does, so there must be some way to animate the changes that you are really after. I hope that doesn't miss the point too badly.