public void setBlendEquation(BlendEquation blendEquation) {
        this.blendEquation = blendEquation;
        cachedHashCode = -1;
    }
Set the blending equation for the color component (RGB).
<p>
The blending equation determines, how the RGB values of the input pixel
will be blended with the RGB values of the pixel already in the color buffer.<br>
For example, {@link BlendEquation#Add} will add the input pixel's color
to the color already in the color buffer:
<br>
<code>Result = Source Color + Destination Color</code>
<p>
<b>Note:</b> This gets only used in {@link BlendMode#Custom} mode.
All other blend modes will ignore this setting.

@param blendEquation The {@link BlendEquation} to use.
jme3-core/src/main/java/com/jme3/material/RenderState.java