Basically I've made a little game, but what I'm wondering is how do I make my created object not go outside the lines of the canvas. When he reaches a border I want him to stop. Any help is appreciated
Hi there i made a little demo game my self. In that game there is what you are looking for. Working demo you can find it here
So what i did was to
1) track user keyboard press
document.onkeydown = function(e) {
e = e || window.event;
if(e.keyCode == "37") player.move("left");
else if(e.keyCode == "38") player.move("up");
else if(e.keyCode == "39") player.move("right");
else if(e.keyCode == "40") player.move("down");
};
2) getting a basic config of the player position (middle in my case)
var player = {
x: Math.round((w/2)/objectSizes),
y: Math.round((h/2)/objectSizes)
}
3) then on the function play.move i track the direction and do all the restrictions
player.move = function(direction) {
/**
* A temporary object to hold the current x, y so if there is a collision with the new coordinates to fallback here
*/
var hold_player = {
x: player.x,
y: player.y
};
/**
* Decide here the direction of the user and do the neccessary changes on the directions
*/
switch(direction) {
case "left":
player.x -= speed / modifier;
if(player.currentDirection == "stand") {
player.currentDirection = "left-1";
} else if(player.currentDirection == "left-1") {
player.currentDirection = "left-2";
} else if(player.currentDirection == "left-2") {
player.currentDirection = "left-1";
} else {
player.currentDirection = "left-1";
}
break;
case "right":
player.x += speed / modifier;
if(player.currentDirection == "stand") {
player.currentDirection = "right-1";
} else if(player.currentDirection == "right-1") {
player.currentDirection = "right-2";
} else if(player.currentDirection == "right-2") {
player.currentDirection = "right-1";
} else {
player.currentDirection = "right-1";
}
break;
case "up":
player.y -= speed / modifier;
if(player.currentDirection == "stand") {
player.currentDirection = "up-1";
} else if(player.currentDirection == "up-1") {
player.currentDirection = "up-2";
} else if(player.currentDirection == "up-2") {
player.currentDirection = "up-1";
} else {
player.currentDirection = "up-1";
}
break;
case "down":
player.y += speed / modifier;
if(player.currentDirection == "stand") {
player.currentDirection = "down-1";
} else if(player.currentDirection == "down-1") {
player.currentDirection = "down-2";
} else if(player.currentDirection == "down-2") {
player.currentDirection = "down-1";
} else {
player.currentDirection = "down-1";
}
break;
}
/**
* if there is a collision just fallback to the temp object i build before while not change back the direction so we can have a movement
*/
if(check_collision(player.x, player.y)) {
player.x = hold_player.x;
player.y = hold_player.y;
}
/**
* If player finds the coordinates of pokeball the generate new one, play the sound and update the score
*/
if(player.x == pokeball.x && player.y == pokeball.y) { // found a pokeball !! create a new one
console.log("found a pokeball of "+pokeball.spritePosition+"! Bravo! ");
pokePick.pause();
pokePick.currentTime = 0;
pokePick.play();
score += 1;
pokeball.generatePosition();
}
update();
};
Then at last i have this function to check any collision
/**
* Our function that decides if there is a collision on the objects or not
* @function
* @name check_collision
* @param {Integer} x - The x axis
* @param {Integer} y - The y axis
*/
function check_collision(x, y) {
var foundCollision = false;
if(((x > 3 && x < 9) && y == 6) || ((x > 4 && x < 9) && (y == 5 || y == 4 || y == 3))) { //collision on house
console.log("on house");
foundCollision = true;
}
if((x<1 || x>20) ||
(y<2 || y>20) ||
((y > 0 && y < 4) && (x == 20 || x == 19)) || //right corner
((y > 0 && y < 4) && (x == 2 || x == 3)) || //left corner
((y > 18) && (x == 2 || x == 3)) || //left corner
((x > 17) && (y == 19 || y == 20)) || //left corner
((x > 19) && (y == 17 || y == 18)) //left corner 2
) {
console.log("lost on the woods");
foundCollision = true
}
return foundCollision;
}
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