Why is the rest of the map darkened?

[FunkMonkey33]

The HeatMap looks great, but when placed over a base layer it significantly darkens the map such that it's difficult to see what's going on underneath. I'm using the default opacity of 0.6.

It seems like the Heatmap.Canvas is writing black for all the places that don't have data. Is that accurate? Is there a way to turn that off?

Thanks.

[sunng87]

Yes, you can override heatcanvas.bgcolor by an RGBA array before rendering. For example:

heatcanvas.bgcolor = [100,0,0,255]

On changing background color, You may also want change default color schema. Just pass a function to render which takes a value (in range [0,1]) and returns an HSLA array for that value.

[FunkMonkey33]

On changing the color schema: can you explain a little more how the default works? In other words, if I just push in some values at a particular location, what determines the color at that exact location, and what determines the color and thickness of the concentric blobs around that location? Also, what are the range of values that the render function expects (i.e. between [0,1], [0,255] etc.)?

Thanks.

[sunng87]

You can not define a color for a particular location, but a particular value, by overriding the default color schema function. And the default function looks like this: https://github.com/sunng87/heatcanvas/blob/master/heatcanvas.js#L153

For the range, consult the documentation: https://github.com/sunng87/heatcanvas#3-render-the-map