How to implement the rendering of objects of complex shape using HTML5 Canvas?

Question

Canvas

Hello. I want to try my hand at developing a game to explore the possibilities of HTML5.
Question 0:
Is it possible to create canvas objects of complex shapes by loading them from a png file with only non-transparent areas being interpreted?
Question 1:
For example, we uploaded an oval-shaped object (500x300px). Is it possible to cut off a part of an arbitrary shape from it (hitting a bullet shot into an object)?

Answer 1

maybe you should read about canvas and see what others are doing on canvas? Or is reading and googling not an option?

Answer 2

Not entirely clear, but try trying sprites

Answer 3

You can use a black and white image as a mask using 'source-in' globalCompositeOperation. First you draw your mask image to the canvas, then you change the globalCompositeOperation to 'source-in', finally you draw your final image.
Your final image will only be drawn where it overlay the mask.

var ctx = document.getElementById('c').getContext('2d');

ctx.drawImage(YOUR_MASK, 0, 0);
ctx.globalCompositeOperation = 'source-in';
ctx.drawImage(YOUR_IMAGE, 0 , 0);

https://developer.mozilla.org/samples/canvas-tutor...

var dimensions = {width: XXX, height: XXX}, //your dimensions
imageObj = document.getElementById('#image'), //select image for RGB
maskObj = document.getElementById('#mask'), //select B/W-mask
image = imageObj.getImageData(0, 0, dimensions.width, dimensions.height),
alphaData = maskObj.getImageData(0, 0, dimensions.width, dimensions.height).data; //this is a canvas pixel array

for (var i = 3, len = image.data.length; i < len; i = i + 4) {

    image.data[i] =  alphaData[i-1]; //copies blue channel of BW mask into A channel of the image

}

//displayCtx is the 2d drawing context of your canvas
displayCtx.putImageData(image, 0, 0, 0, 0, dimensions.width, dimensions.height);