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3d_texture.htm
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<html>
<head>
<title>JavaScript Wolfenstein 3D Engine - Textured walls</title>
<!--
/*
* Example code from the article at: http://dev.opera.com/articles/view/creating-pseudo-3d-games-with-html-5-can-1/
* Copyright (c) 2008 Jacob Seidelin, [email protected], http://blog.nihilogic.dk/
* The code is available to use under the terms of the MIT License
* [http://www.opensource.org/licenses/mit-license.php]
*/
-->
<style>
div#minimapcontainer {
}
canvas#minimap {
position : absolute;
}
canvas#minimapobjects {
position : absolute;
}
div#floor {
position : absolute;
width : 100%;
height : 100%;
background-color : rgb(128,128,128);
}
div#ceiling {
position : absolute;
width : 100%;
height : 50%;
background-color : rgb(96,96,96);
}
#screen {
position : relative;
width : 320px;
height : 200px;
border : 1px solid black;
overflow : hidden;
}
</style>
<script src="excanvas.js" type="text/javascript"></script>
</head>
<body>
<div id="screen">
<div id="floor"></div>
<div id="ceiling"></div>
</div>
<div id="minimapcontainer">
<canvas id="minimap"></canvas>
<canvas id="minimapobjects"></canvas>
</div>
<script type="text/javascript">
var $ = function(id) { return document.getElementById(id); };
var dc = function(tag) { return document.createElement(tag); };
var map = [
[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],
[1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,3,0,3,0,0,1,1,1,2,1,1,1,1,1,2,1,1,1,2,1,0,0,0,0,0,0,0,0,1],
[1,0,0,3,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,1,1,1,1,1],
[1,0,0,3,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,3,0,4,0,0,0,0,0,0,2,3,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
[1,0,0,3,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,1,1,1,1,1],
[1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,0,0,0,0,0,0,3,3,3,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
[1,0,0,0,0,0,0,0,0,3,3,3,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,0,0,0,0,0,0,3,3,3,0,0,3,3,3,0,0,0,0,0,0,0,0,0,3,1,1,1,1,1],
[1,0,0,0,0,0,0,0,0,3,3,3,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,4,0,0,4,2,0,2,2,2,2,2,2,2,2,0,2,4,4,0,0,4,0,0,0,0,0,0,0,1],
[1,0,0,4,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,4,0,0,0,0,0,0,0,1],
[1,0,0,4,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,4,0,0,0,0,0,0,0,1],
[1,0,0,4,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,4,0,0,0,0,0,0,0,1],
[1,0,0,4,3,3,4,2,2,2,2,2,2,2,2,2,2,2,2,2,4,3,3,4,0,0,0,0,0,0,0,1],
[1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]
];
var player = {
x : 16, // current x, y position
y : 10,
dir : 0, // the direction that the player is turning, either -1 for left or 1 for right.
rot : 0, // the current angle of rotation
speed : 0, // is the playing moving forward (speed = 1) or backwards (speed = -1).
moveSpeed : 0.18, // how far (in map units) does the player move each step/update
rotSpeed : 6 * Math.PI / 180, // how much does the player rotate each step/update (in radians)
strafe: 0
}
var mapWidth = 0;
var mapHeight = 0;
var miniMapScale = 8;
var screenWidth = 320;
var screenHeight = 200;
var stripWidth = 2;
var fov = 60 * Math.PI / 180;
var numRays = Math.ceil(screenWidth / stripWidth);
var fovHalf = fov / 2;
var viewDist = (screenWidth/2) / Math.tan((fov / 2));
var twoPI = Math.PI * 2;
var numTextures = 4;
function init() {
mapWidth = map[0].length;
mapHeight = map.length;
bindKeys();
initScreen();
drawMiniMap();
gameCycle();
}
var screenStrips = [];
function initScreen() {
var screen = $("screen");
for (var i=0;i<screenWidth;i+=stripWidth) {
var strip = dc("div");
strip.style.position = "absolute";
strip.style.left = i + "px";
strip.style.width = stripWidth+"px";
strip.style.height = "0px";
strip.style.overflow = "hidden";
strip.style.backgroundColor = "magenta";
var img = new Image();
img.src = (window.opera ? "walls_19color.png" : "walls.png");
img.style.position = "absolute";
img.style.left = "0px";
strip.appendChild(img);
strip.img = img; // assign the image to a property on the strip element so we have easy access to the image later
screenStrips.push(strip);
screen.appendChild(strip);
}
}
// bind keyboard events to game functions (movement, etc)
function bindKeys() {
document.onkeydown = function(e) {
e = e || window.event;
switch (e.keyCode) { // which key was pressed?
case 87: //w
case 38: // up, move player forward, ie. increase speed
player.speed = 1;
break;
case 83: //s
case 40: // down, move player backward, set negative speed
player.speed = -1;
break;
case 68: // d, rotate player left
player.dir = 1;
break;
case 65: // a, rotate player right
player.dir = -1;
break;
case 37: //left
player.strafe = 1;
player.speed = -1;
break;
case 39: //right
player.strafe = 1;
player.speed = 1;
break;
}
}
document.onkeyup = function(e) {
e = e || window.event;
console.log(e.keyCode);
switch (e.keyCode) {
case 37: //left
case 39: //right
case 83: //s
case 87: //w
case 38: //up
case 40: //down
player.speed = 0; // stop the player movement when up/down key is released
player.strafe = 0;
break;
case 65: //a
case 68: //d
player.dir = 0;
break;
}
}
}
function gameCycle() {
move();
updateMiniMap();
castRays();
setTimeout(gameCycle,1000/30); // aim for 30 FPS
}
function castRays() {
var stripIdx = 0;
for (var i=0;i<numRays;i++) {
// where on the screen does ray go through?
var rayScreenPos = (-numRays/2 + i) * stripWidth;
// the distance from the viewer to the point on the screen, simply Pythagoras.
var rayViewDist = Math.sqrt(rayScreenPos*rayScreenPos + viewDist*viewDist);
// the angle of the ray, relative to the viewing direction.
// right triangle: a = sin(A) * c
var rayAngle = Math.asin(rayScreenPos / rayViewDist);
castSingleRay(
player.rot + rayAngle, // add the players viewing direction to get the angle in world space
stripIdx++
);
}
}
function castSingleRay(rayAngle, stripIdx) {
// first make sure the angle is between 0 and 360 degrees
rayAngle %= twoPI;
if (rayAngle < 0) rayAngle += twoPI;
// moving right/left? up/down? Determined by which quadrant the angle is in.
var right = (rayAngle > twoPI * 0.75 || rayAngle < twoPI * 0.25);
var up = (rayAngle < 0 || rayAngle > Math.PI);
var wallType = 0;
// only do these once
var angleSin = Math.sin(rayAngle);
var angleCos = Math.cos(rayAngle);
var dist = 0; // the distance to the block we hit
var xHit = 0; // the x and y coord of where the ray hit the block
var yHit = 0;
var textureX; // the x-coord on the texture of the block, ie. what part of the texture are we going to render
var wallX; // the (x,y) map coords of the block
var wallY;
var wallIsHorizontal = false;
// first check against the vertical map/wall lines
// we do this by moving to the right or left edge of the block we're standing in
// and then moving in 1 map unit steps horizontally. The amount we have to move vertically
// is determined by the slope of the ray, which is simply defined as sin(angle) / cos(angle).
var slope = angleSin / angleCos; // the slope of the straight line made by the ray
var dXVer = right ? 1 : -1; // we move either 1 map unit to the left or right
var dYVer = dXVer * slope; // how much to move up or down
var x = right ? Math.ceil(player.x) : Math.floor(player.x); // starting horizontal position, at one of the edges of the current map block
var y = player.y + (x - player.x) * slope; // starting vertical position. We add the small horizontal step we just made, multiplied by the slope.
while (x >= 0 && x < mapWidth && y >= 0 && y < mapHeight) {
var wallX = Math.floor(x + (right ? 0 : -1));
var wallY = Math.floor(y);
// is this point inside a wall block?
if (map[wallY][wallX] > 0) {
var distX = x - player.x;
var distY = y - player.y;
dist = distX*distX + distY*distY; // the distance from the player to this point, squared.
wallType = map[wallY][wallX]; // we'll remember the type of wall we hit for later
textureX = y % 1; // where exactly are we on the wall? textureX is the x coordinate on the texture that we'll use later when texturing the wall.
if (!right) textureX = 1 - textureX; // if we're looking to the left side of the map, the texture should be reversed
xHit = x; // save the coordinates of the hit. We only really use these to draw the rays on minimap.
yHit = y;
wallIsHorizontal = true;
break;
}
x += dXVer;
y += dYVer;
}
// now check against horizontal lines. It's basically the same, just "turned around".
// the only difference here is that once we hit a map block,
// we check if there we also found one in the earlier, vertical run. We'll know that if dist != 0.
// If so, we only register this hit if this distance is smaller.
var slope = angleCos / angleSin;
var dYHor = up ? -1 : 1;
var dXHor = dYHor * slope;
var y = up ? Math.floor(player.y) : Math.ceil(player.y);
var x = player.x + (y - player.y) * slope;
while (x >= 0 && x < mapWidth && y >= 0 && y < mapHeight) {
var wallY = Math.floor(y + (up ? -1 : 0));
var wallX = Math.floor(x);
if (map[wallY][wallX] > 0) {
var distX = x - player.x;
var distY = y - player.y;
var blockDist = distX*distX + distY*distY;
if (!dist || blockDist < dist) {
dist = blockDist;
xHit = x;
yHit = y;
wallType = map[wallY][wallX];
textureX = x % 1;
if (up) textureX = 1 - textureX;
}
break;
}
x += dXHor;
y += dYHor;
}
if (dist) {
//drawRay(xHit, yHit);
var strip = screenStrips[stripIdx];
dist = Math.sqrt(dist);
// use perpendicular distance to adjust for fish eye
// distorted_dist = correct_dist / cos(relative_angle_of_ray)
dist = dist * Math.cos(player.rot - rayAngle);
// now calc the position, height and width of the wall strip
// "real" wall height in the game world is 1 unit, the distance from the player to the screen is viewDist,
// thus the height on the screen is equal to wall_height_real * viewDist / dist
var height = Math.round(viewDist / dist);
// width is the same, but we have to stretch the texture to a factor of stripWidth to make it fill the strip correctly
var width = height * stripWidth;
// top placement is easy since everything is centered on the x-axis, so we simply move
// it half way down the screen and then half the wall height back up.
var top = Math.round((screenHeight - height) / 2);
strip.style.height = height+"px";
strip.style.top = top+"px";
strip.img.style.height = Math.floor(height * numTextures) + "px";
strip.img.style.width = Math.floor(width*2) +"px";
strip.img.style.top = -Math.floor(height * (wallType-1)) + "px";
var texX = Math.round(textureX*width);
if (texX > width - stripWidth)
texX = width - stripWidth;
strip.img.style.left = -texX + "px";
}
}
function drawRay(rayX, rayY) {
var miniMapObjects = $("minimapobjects");
var objectCtx = miniMapObjects.getContext("2d");
objectCtx.strokeStyle = "rgba(0,100,0,0.3)";
objectCtx.lineWidth = 0.5;
objectCtx.beginPath();
objectCtx.moveTo(player.x * miniMapScale, player.y * miniMapScale);
objectCtx.lineTo(
rayX * miniMapScale,
rayY * miniMapScale
);
objectCtx.closePath();
objectCtx.stroke();
}
function move() {
var moveStep = player.speed * player.moveSpeed; // player will move this far along the current direction vector
player.rot += player.dir * player.rotSpeed; // add rotation if player is rotating (player.dir != 0)
// make sure the angle is between 0 and 360 degrees
//while (player.rot < 0) player.rot += twoPI;
//while (player.rot >= twoPI) player.rot -= twoPI;
if(player.strafe == 0) {
var newX = player.x + Math.cos(player.rot) * moveStep; // calculate new player position with simple trigonometry
var newY = player.y + Math.sin(player.rot) * moveStep;
} else {
var newX = player.x + Math.sin(player.rot) * moveStep; // calculate new player position with simple trigonometry
var newY = player.y + Math.cos(player.rot) * moveStep;
}
if (isBlocking(newX, newY)) { // are we allowed to move to the new position?
return; // no, bail out.
}
player.x = newX; // set new position
player.y = newY;
}
function isBlocking(x,y) {
// first make sure that we cannot move outside the boundaries of the level
if (y < 0 || y >= mapHeight || x < 0 || x >= mapWidth)
return true;
// return true if the map block is not 0, ie. if there is a blocking wall.
return (map[Math.floor(y)][Math.floor(x)] != 0);
}
function updateMiniMap() {
var miniMap = $("minimap");
var miniMapObjects = $("minimapobjects");
var objectCtx = miniMapObjects.getContext("2d");
miniMapObjects.width = miniMapObjects.width;
objectCtx.fillStyle = "red";
objectCtx.fillRect( // draw a dot at the current player position
player.x * miniMapScale - 2,
player.y * miniMapScale - 2,
4, 4
);
objectCtx.strokeStyle = "red";
objectCtx.beginPath();
objectCtx.moveTo(player.x * miniMapScale, player.y * miniMapScale);
objectCtx.lineTo(
(player.x + Math.cos(player.rot) * 4) * miniMapScale,
(player.y + Math.sin(player.rot) * 4) * miniMapScale
);
objectCtx.closePath();
objectCtx.stroke();
}
function drawMiniMap() {
// draw the topdown view minimap
var miniMap = $("minimap"); // the actual map
var miniMapCtr = $("minimapcontainer"); // the container div element
var miniMapObjects = $("minimapobjects"); // the canvas used for drawing the objects on the map (player character, etc)
miniMap.width = mapWidth * miniMapScale; // resize the internal canvas dimensions
miniMap.height = mapHeight * miniMapScale; // of both the map canvas and the object canvas
miniMapObjects.width = miniMap.width;
miniMapObjects.height = miniMap.height;
var w = (mapWidth * miniMapScale) + "px" // minimap CSS dimensions
var h = (mapHeight * miniMapScale) + "px"
miniMap.style.width = miniMapObjects.style.width = miniMapCtr.style.width = w;
miniMap.style.height = miniMapObjects.style.height = miniMapCtr.style.height = h;
var ctx = miniMap.getContext("2d");
ctx.fillStyle = "white";
ctx.fillRect(0,0,miniMap.width,miniMap.height);
// loop through all blocks on the map
for (var y=0;y<mapHeight;y++) {
for (var x=0;x<mapWidth;x++) {
var wall = map[y][x];
if (wall > 0) { // if there is a wall block at this (x,y) ...
ctx.fillStyle = "rgb(200,200,200)";
ctx.fillRect( // ... then draw a block on the minimap
x * miniMapScale,
y * miniMapScale,
miniMapScale,miniMapScale
);
}
}
}
updateMiniMap();
}
setTimeout(init, 1);
</script>
</body>