String[] texNames = { "img1.png", "img2.png", "img3.png" };
int      texLen   = texNames.length;
PImage[] textures = new PImage[texLen];

void setup() {
	size(500,500,P3D);

	for (int i = 0; i < texLen; ++i) {
		textures[i] = loadImage(texNames[i]);
	}
}

void draw() {
	background(#CCCCCC);
	textureMode(NORMAL);

	pushMatrix();
		translate(width/2,height/2);
		scale(300);

		strokeWeight(0);
		noStroke();
		noFill();
		tint(#FF3300);

		beginShape(QUADS);
			texture(textures[frameCount%texLen]);
			vertex(-0.5, -0.5,   0,0);
			vertex( 0.5, -0.5,   1,0);
			vertex( 0.5,  0.5,   1,1);
			vertex(-0.5,  0.5,   0,1);
		endShape();
	popMatrix();
}