DisplaceX

Function

This is a general purpose warping tool, similar to WarpX, except you can access a second warping image to control the distribution of a warp. You can put any formula you want into the x and y fields to do custom warps. You can also create multi-line expressions in this function. See the second script tutorial for an extended example of the DisplaceX function.

Parameters
Type
Defaults
Function
oversampling
int
1 The actual number of samples per pixel equals this number squared. For better antialiasing, increase the number.
x,yExpression
float
x, y

The expression for where the pixel information is pulled from. Expressions of x and y return the same image. Expressions of x+5, y+5 will pull the color from the pixel 5 units up and to the right of the current pixel. You can access the values of the warping image (the second one) with r,g,b,a, and z.

Example expressions:
"x*r"
"x+((r-.5)*30*r)"
"x+cos(y/140)*70*g"
"x+r*r*cos(x*y/100)*100"

x,yDelta
float
0, xDelta They set the maximum distance that any pixel is expected to move, but doesn't actually move it. From any given pixel, it may be affected by any pixel within the Delta distance. This means it has to consider a much greater amount of pixels that possibly may effect the currently rendered pixel. This is bad. However, if you set a Delta value to too small an amount, you will get errors if your expression tells the pixel to move beyond that limit. Therefore, it always takes some testing to balance between speed with errors, or accuracy with drastically slower renders. Our advice: start small and increase the size until the errors disappear.


Synopsis

image DisplaceX( 
  image,
  image,
  int oversampling, 
  float expression xExpression,
  float expression yExpression,
  int xDelta,
  int yDelta
);


Script

image = DisplaceX(
  image,
  image,
  oversampling, 
  xExpression,
  yExpression,
  xDelta,
  yDelta
);

For multi-line expressions:
image = DisplaceX(
  image,
  image,
  oversampling, 
  {{ xExpr1, xExpr2, ... xExprN }},
  yExpression,
  xDelta,
  yDelta
);


Command Line

shake -displacex oversampling xExpression etc...

See Also
Randomize, Rand, Turbulate