Test out each of the blend modes; need to run 3x, one for each render mode.

render_all_blend_modes.pyde

# Code for https://github.com/processing/processing/issues/4376
# See processing/core/src/processing/core/PConstants.java for render/blend mode constants.
labels = 'REPLACE, BLEND, ADD, SUBTRACT, LIGHTEST, DARKEST, DIFFERENCE, EXCLUSION, MULTIPLY, SCREEN, OVERLAY, HARD_LIGHT, SOFT_LIGHT, DODGE, BURN'.split(', ')                                                                                                                                                                    
blend_modes = [REPLACE, BLEND, ADD, SUBTRACT, LIGHTEST, DARKEST, DIFFERENCE, EXCLUSION, MULTIPLY, SCREEN, OVERLAY, HARD_LIGHT, SOFT_LIGHT, DODGE, BURN]
blend_mode_names = dict(zip(blend_modes, labels))
render_modes = [JAVA2D, P2D, P3D]
render_mode = render_modes[0]   

def setup():
    size(300, 1000, render_mode)
    noLoop()
    
def draw():
    background(255)
    noStroke()
            
    colors = [color(255, 0, 0, 255), color(0, 255, 0, 255), color(0, 0, 255, 255)] # R, G, B
    margin = 20
    h_inc = (height - 2*margin) / len(blend_modes)
    h = margin
    r = h_inc / 2
    fill(0)
    text("Render Mode: %s" % render_mode, margin, margin)
    for blend_mode in blend_modes:
        pushStyle()
        blendMode(REPLACE)
        fill(0)
        text("Blend Mode: %s (%s)" % (blend_mode_names[blend_mode], blend_mode), margin, h + margin)              
        rect(width/2, h + margin + 1, width, h_inc - margin - 1)
        popStyle()
        
        blendMode(blend_mode)  
        for i, c in enumerate(colors, 1):
            fill(c)
            x = 2*margin + .5*i*r
            y = h + margin/2 + r
            ellipse(x, y, r, r)
            ellipse(x + width/2, y, r, r)
        h += h_inc
   
    saveFrame('issue_4376_%s.png' % (render_mode))