Eyes
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Eyes
This code uses instances of the PVector class (and the handy functions inside that class) to draw two eyes that follow the mouse. Creepy! 
PVector leftEye; PVector rightEye; void setup(){ size(200, 100); leftEye = new PVector(width*.25, height*.5); rightEye = new PVector(width*.75, height*.5); } void draw(){ background(200); PVector mouseVector = new PVector(mouseX, mouseY); PVector leftPupil = leftEye.copy().add(mouseVector.copy().sub(leftEye).setMag(10)); PVector rightPupil = rightEye.copy().add(mouseVector.copy().sub(rightEye).setMag(10)); fill(255); ellipse(leftEye.x, leftEye.y, 50, 50); ellipse(rightEye.x, rightEye.y, 50, 50); fill(0); ellipse(leftPupil.x, leftPupil.y, 20, 20); ellipse(rightPupil.x, rightPupil.y, 20, 20); } 
We are doing a lot with just a couple lines of code, so let’s break that down into smaller steps. Take this line:
PVector leftPupil = leftEye.copy().add(mouseVector.copy().sub(leftEye).setMag(10)); This line can be broken up into its individual steps, that way we can better see what’s going on:
//copy the left eye so we don't change where we draw it when we call add() PVector copyOfLeftEye = leftEye.copy(); //copy the mouseVector so we don't change it when we call sub() PVector copyOfMouseVector = mouseVector.copy(); //subtract leftEye from copyOfMouseVector to get the direction to look PVector difference = copyOfMouseVector.sub(leftEye); //set the magnitude of the difference so the pupil doesn't go outside the eye PVector scaledDifference = difference.setMag(10); //add the scaledDifference to copyOfLeftEye so the pupil is centered around the eye PVector leftPupil = copyOfLeftEye.add(scaledDifference); 
Tweak Ideas
- Try doing this without the
PVectorclass. Hint: basic trig comes in handy! - Make the eyes look more realistic. Add iris colors, make them shaped like real eyes, add lashes, blinking, etc. Try to make it really pretty- or really creepy!
- Make it so whenever the user clicks, a new eye is added.
- Create faces that follow the mouse with their eyes, frown (or smile) when the mouse gets too close, look surprised when the user clicks, etc. Get creative!
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