Blend CHOP

From TouchDesigner 088 Wiki


The Blend CHOP combines two or more CHOPs in input 2, 3 and so on, by using a set of blending channels in input 1. The blending channels cause different strengths of the CHOPs to contribute to the output of the CHOP. It works like the Blend SOP.

The first channel of input 2 is blended with the first channel of input 3 and input 4 and so on.

Input 1 acts as the control input, which contains the blend weight channels for the rest of the inputs. In it there is one channel for each of the blended CHOPs coming in on input 2, 3 and so on.

The first channel in input 1 is input 2's blend weight, the second channel in input 1 is the input 3's blend weight, and so on. There should be as many blend channels in input 1 as there are inputs, excluding input 1.

The interval of the output of the CHOP is the interval of input 1 (the blend channels).

If input 2 onwards are just poses, it's acceptable, as the CHOP blends between poses by using extend conditions.

Note: This CHOP is optimized and doesn't cook inputs that have zero weight.

PythonIcon.png blendCHOP_Class


Method - The blend method:

  • Proportional - Each blend source contributes to the result according to its blend weight. If the blend weights do not add up to one, they are scaled so that they do.
  • Difference - In this default behavior of the Blend CHOP, the input 2 is always the "base". There are blend channels for all the other inputs, and when they are all zero, you get base. If any one blend channel is 1 and the others are zero, then your output is the same as the input that corresponds to that blend channel.
  • Quaternion - The first input is used to control the proportional blending of the second two inputs using quaternions. Blending rotation channels properly involves grouping the channels into quaternion groups with the Attribute CHOP before using this or similar quaternion options.

Omit First Weight Channel - When using the Differencing method, the weight channel for the base input has no effect, so the channel is omitted if this option is On.

Advantages of Difference Method

Each blend input affects the result without reducing the effect of the others. You can exaggerate beyond each of the inputs by setting their Blend > 1, and you can also use negative values. When all blend channels are 0, you get smooth transitions as any of the blend channels ease out of zero.

Standard Options and Local Variables

No Local Variables