Provides support for color-coding-based picking and highlighting. In particular, supports picking a specific instance in an instanced draw call and highlighting an instance based on its picking color, and correspondingly, supports picking and highlighting groups of primitives with the same picking color in non-instanced draw-calls

Color based picking lets the application draw a primitive with a color that can later be used to index this specific primitive.

Highlighting allows application to specify a picking color corresponding to an object that need to be highlighted and the highlight color to be used.

In your vertex shader, your inform the picking module what object we are currently rendering by supplying a picking color, perhaps from an attribute.

attribute vec3 aPickingColor;
main() {
  picking_setColor(aPickingColor);
  ...
}

In your fragment shader, you simply apply (call) the picking_filterPickingColor filter function at the very end of the shader. This will return the normal color, or the highlight color, or the picking color, as appropriate.

main() {
  gl_FragColor = ...
  gl_FragColor = picking_filterPickingColor(gl_FragColor);
}

If you would like to apply the highlight color to the currently selected element call picking_filterHighlightColor before calling picking_filterPickingColor. You can also apply other filters on the non-picking color (vertex or highlight color) by placing those instruction between these two function calls.

main() {
  gl_FragColor = picking_filterHighlightColor(color);
   ... apply any filters on gl_FragColor ...
 gl_FragColor = picking_filterPickingColor(gl_FragColor);
}

getUniforms takes an object takes a set of key/value pairs, returns an object with key/value pairs representing the uniforms that the picking module shaders need.

getUniforms(opts) opts can contain following keys:

• pickingSelectedColorValid (boolean) - When true current instance picking color is ignored, hence no instance is highlighted.
• pickingSelectedColor (array) - Picking color of the currently selected instance.
• pickingHighlightColor (array)- Color used to highlight the currently selected instance.
• pickingActive=false (boolean) - When true, renders the picking colors instead of the normal colors. Normally only used with an off-screen framebuffer during picking. Default value is false.

Note that the selected item will be rendered using pickingHighlightColor, if blending is enabled for the draw, alpha channel can be used to control the blending result.

Sets the color that will be returned by the fragment shader if color based picking is enabled. Typically set from a pickingColor uniform or a pickingColors attribute (e.g. when using instanced rendering, to identify the actual instance that was picked).

If picking active, returns the current vertex's picking color set by picking_setPickingColor, otherwise returns its argument unmodified.

vec4 picking_filterPickingColor(vec4 color)

Returns picking highlight color if the pixel belongs to currently selected model, otherwise returns its argument unmodified.

vec4 picking_filterHighlightColor(vec4 color)

• It is strongly recommended that picking_filterPickingColor is called last in a fragment shader, as the picking color (returned when picking is enabled) must not be modified in any way (and alpha must remain 1) or picking results will not be correct.