Provides support for color-coding-based picking. In particular, supports picking a specific instance in an instanced draw call.
Color based picking lets the application draw a primitive with a color that can later be used to index this specific primitive.
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_setPickingColor(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 returns an object with key/value pairs representing the uniforms that the picking module shaders need.
getUniforms({pickingActive, ...})
pickingActive=false (boolean) - Renders the picking colors instead of the normal colors. Normally only used with an off-screen framebuffer during picking.pickingSelectedColor=null (array|null) - The picking color of the selected (highlighted) object.pickingHighlightColor= [0, 255, 255, 255] (array) - Color used to highlight the currently selected object.pickingAttribute=false (boolean) - Renders a color that encodes an attribute value. Normally only used with an off-screen framebuffer during picking.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).
void picking_setPickingColor(vec3 pickingColor)
Sets the attribute value that needs to be picked.
void picking_setPickingAttribute(float value)
void picking_setPickingAttribute(vec2 value)
void picking_setPickingAttribute(vec3 value)
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)
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.