littlejsengine
Version:
LittleJS - Tiny and Fast HTML5 Game Engine
622 lines (570 loc) • 24 kB
JavaScript
/**
* LittleJS Drawing System
* - Hybrid system with both Canvas2D and WebGL available
* - Super fast tile sheet rendering with WebGL
* - Can apply rotation, mirror, color and additive color
* - Font rendering system with built in engine font
* - Many useful utility functions
*
* LittleJS uses a hybrid rendering solution with the best of both Canvas2D and WebGL.
* There are 3 canvas/contexts available to draw to...
* mainCanvas - 2D background canvas, non WebGL stuff like tile layers are drawn here.
* glCanvas - Used by the accelerated WebGL batch rendering system.
* overlayCanvas - Another 2D canvas that appears on top of the other 2 canvases.
*
* The WebGL rendering system is very fast with some caveats...
* - Switching blend modes (additive) or textures causes another draw call which is expensive in excess
* - Group additive rendering together using renderOrder to mitigate this issue
*
* The LittleJS rendering solution is intentionally simple, feel free to adjust it for your needs!
* @namespace Draw
*/
'use strict';
/** The primary 2D canvas visible to the user
* @type {HTMLCanvasElement}
* @memberof Draw */
let mainCanvas;
/** 2d context for mainCanvas
* @type {CanvasRenderingContext2D}
* @memberof Draw */
let mainContext;
/** A canvas that appears on top of everything the same size as mainCanvas
* @type {HTMLCanvasElement}
* @memberof Draw */
let overlayCanvas;
/** 2d context for overlayCanvas
* @type {CanvasRenderingContext2D}
* @memberof Draw */
let overlayContext;
/** The size of the main canvas (and other secondary canvases)
* @type {Vector2}
* @memberof Draw */
let mainCanvasSize = vec2();
/** Array containing texture info for batch rendering system
* @type {Array<TextureInfo>}
* @memberof Draw */
let textureInfos = [];
// Keep track of how many draw calls there were each frame for debugging
let drawCount;
///////////////////////////////////////////////////////////////////////////////
/**
* Create a tile info object using a grid based system
* - This can take vecs or floats for easier use and conversion
* - If an index is passed in, the tile size and index will determine the position
* @param {Vector2|number} [pos=0] - Index of tile in sheet
* @param {Vector2|number} [size=tileSizeDefault] - Size of tile in pixels
* @param {number} [textureIndex] - Texture index to use
* @param {number} [padding] - How many pixels padding around tiles
* @return {TileInfo}
* @example
* tile(2) // a tile at index 2 using the default tile size of 16
* tile(5, 8) // a tile at index 5 using a tile size of 8
* tile(1, 16, 3) // a tile at index 1 of size 16 on texture 3
* tile(vec2(4,8), vec2(30,10)) // a tile at index (4,8) with a size of (30,10)
* @memberof Draw
*/
function tile(pos=vec2(), size=tileSizeDefault, textureIndex=0, padding=0)
{
if (headlessMode)
return new TileInfo;
// if size is a number, make it a vector
if (typeof size === 'number')
{
ASSERT(size > 0);
size = vec2(size);
}
// use pos as a tile index
const textureInfo = textureInfos[textureIndex];
ASSERT(!!textureInfo, 'Texture not loaded');
const sizePadded = size.add(vec2(padding*2));
if (typeof pos === 'number')
{
const cols = textureInfo.size.x / sizePadded.x |0;
pos = cols>0 ? vec2(pos%cols, pos/cols|0) : vec2();
}
pos = vec2(pos.x*sizePadded.x+padding, pos.y*sizePadded.y+padding);
// return a tile info object
return new TileInfo(pos, size, textureIndex, padding);
}
/**
* Tile Info - Stores info about how to draw a tile
*/
class TileInfo
{
/** Create a tile info object
* @param {Vector2} [pos=(0,0)] - Top left corner of tile in pixels
* @param {Vector2} [size=tileSizeDefault] - Size of tile in pixels
* @param {number} [textureIndex] - Texture index to use
* @param {number} [padding] - How many pixels padding around tiles
*/
constructor(pos=vec2(), size=tileSizeDefault, textureIndex=0, padding=0)
{
/** @property {Vector2} - Top left corner of tile in pixels */
this.pos = pos.copy();
/** @property {Vector2} - Size of tile in pixels */
this.size = size.copy();
/** @property {number} - Texture index to use */
this.textureIndex = textureIndex;
/** @property {number} - How many pixels padding around tiles */
this.padding = padding;
}
/** Returns a copy of this tile offset by a vector
* @param {Vector2} offset - Offset to apply in pixels
* @return {TileInfo}
*/
offset(offset)
{ return new TileInfo(this.pos.add(offset), this.size, this.textureIndex); }
/** Returns a copy of this tile offset by a number of animation frames
* @param {number} frame - Offset to apply in animation frames
* @return {TileInfo}
*/
frame(frame)
{
ASSERT(typeof frame == 'number');
return this.offset(vec2(frame*(this.size.x+this.padding*2), 0));
}
/** Returns the texture info for this tile
* @return {TextureInfo}
*/
getTextureInfo()
{ return textureInfos[this.textureIndex]; }
}
/** Texture Info - Stores info about each texture */
class TextureInfo
{
/**
* Create a TextureInfo, called automatically by the engine
* @param {HTMLImageElement} image
*/
constructor(image)
{
/** @property {HTMLImageElement} - image source */
this.image = image;
/** @property {Vector2} - size of the image */
this.size = vec2(image.width, image.height);
/** @property {WebGLTexture} - webgl texture */
this.glTexture = glEnable && glCreateTexture(image);
}
}
///////////////////////////////////////////////////////////////////////////////
/** Convert from screen to world space coordinates
* @param {Vector2} screenPos
* @return {Vector2}
* @memberof Draw */
function screenToWorld(screenPos)
{
return new Vector2
(
(screenPos.x - mainCanvasSize.x/2 + .5) / cameraScale + cameraPos.x,
(screenPos.y - mainCanvasSize.y/2 + .5) / -cameraScale + cameraPos.y
);
}
/** Convert from world to screen space coordinates
* @param {Vector2} worldPos
* @return {Vector2}
* @memberof Draw */
function worldToScreen(worldPos)
{
return new Vector2
(
(worldPos.x - cameraPos.x) * cameraScale + mainCanvasSize.x/2 - .5,
(worldPos.y - cameraPos.y) * -cameraScale + mainCanvasSize.y/2 - .5
);
}
/** Get the camera's visible area in world space
* @return {Vector2}
* @memberof Draw */
function getCameraSize() { return mainCanvasSize.scale(1/cameraScale); }
/** Draw textured tile centered in world space, with color applied if using WebGL
* @param {Vector2} pos - Center of the tile in world space
* @param {Vector2} [size=(1,1)] - Size of the tile in world space
* @param {TileInfo}[tileInfo] - Tile info to use, untextured if undefined
* @param {Color} [color=(1,1,1,1)] - Color to modulate with
* @param {number} [angle] - Angle to rotate by
* @param {boolean} [mirror] - If true image is flipped along the Y axis
* @param {Color} [additiveColor=(0,0,0,0)] - Additive color to be applied
* @param {boolean} [useWebGL=glEnable] - Use accelerated WebGL rendering
* @param {boolean} [screenSpace=false] - If true the pos and size are in screen space
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context] - Canvas 2D context to draw to
* @memberof Draw */
function drawTile(pos, size=vec2(1), tileInfo, color=new Color,
angle=0, mirror, additiveColor=new Color(0,0,0,0), useWebGL=glEnable, screenSpace, context)
{
ASSERT(!context || !useWebGL, 'context only supported in canvas 2D mode');
ASSERT(typeof tileInfo !== 'number' || !tileInfo,
'this is an old style calls, to fix replace it with tile(tileIndex, tileSize)');
ASSERT(isVector2(pos) && isVector2(size));
ASSERT(isColor(color) && isColor(additiveColor));
const textureInfo = tileInfo && tileInfo.getTextureInfo();
if (useWebGL)
{
if (screenSpace)
{
// convert to world space
pos = screenToWorld(pos);
size = size.scale(1/cameraScale);
}
if (textureInfo)
{
// calculate uvs and render
const sizeInverse = vec2(1).divide(textureInfo.size);
const x = tileInfo.pos.x * sizeInverse.x;
const y = tileInfo.pos.y * sizeInverse.y;
const w = tileInfo.size.x * sizeInverse.x;
const h = tileInfo.size.y * sizeInverse.y;
const tileImageFixBleed = sizeInverse.scale(tileFixBleedScale);
glSetTexture(textureInfo.glTexture);
glDraw(pos.x, pos.y, mirror ? -size.x : size.x, size.y, angle,
x + tileImageFixBleed.x, y + tileImageFixBleed.y,
x - tileImageFixBleed.x + w, y - tileImageFixBleed.y + h,
color.rgbaInt(), additiveColor.rgbaInt());
}
else
{
// if no tile info, force untextured
glDraw(pos.x, pos.y, size.x, size.y, angle, 0, 0, 0, 0, 0, color.rgbaInt());
}
}
else
{
// normal canvas 2D rendering method (slower)
showWatermark && ++drawCount;
size = vec2(size.x, -size.y); // fix upside down sprites
drawCanvas2D(pos, size, angle, mirror, (context)=>
{
if (textureInfo)
{
// calculate uvs and render
const x = tileInfo.pos.x + tileFixBleedScale;
const y = tileInfo.pos.y + tileFixBleedScale;
const w = tileInfo.size.x - 2*tileFixBleedScale;
const h = tileInfo.size.y - 2*tileFixBleedScale;
context.globalAlpha = color.a; // only alpha is supported
context.drawImage(textureInfo.image, x, y, w, h, -.5, -.5, 1, 1);
context.globalAlpha = 1; // set back to full alpha
}
else
{
// if no tile info, force untextured
context.fillStyle = color.toString();
context.fillRect(-.5, -.5, 1, 1);
}
}, screenSpace, context);
}
}
/** Draw colored rect centered on pos
* @param {Vector2} pos
* @param {Vector2} [size=(1,1)]
* @param {Color} [color=(1,1,1,1)]
* @param {number} [angle]
* @param {boolean} [useWebGL=glEnable]
* @param {boolean} [screenSpace=false]
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context]
* @memberof Draw */
function drawRect(pos, size, color, angle, useWebGL, screenSpace, context)
{
drawTile(pos, size, undefined, color, angle, false, undefined, useWebGL, screenSpace, context);
}
/** Draw colored line between two points
* @param {Vector2} posA
* @param {Vector2} posB
* @param {number} [thickness]
* @param {Color} [color=(1,1,1,1)]
* @param {boolean} [useWebGL=glEnable]
* @param {boolean} [screenSpace=false]
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context]
* @memberof Draw */
function drawLine(posA, posB, thickness=.1, color, useWebGL, screenSpace, context)
{
const halfDelta = vec2((posB.x - posA.x)/2, (posB.y - posA.y)/2);
const size = vec2(thickness, halfDelta.length()*2);
drawRect(posA.add(halfDelta), size, color, halfDelta.angle(), useWebGL, screenSpace, context);
}
/** Draw colored polygon using passed in points
* @param {Array<Vector2>} points - Array of Vector2 points
* @param {Color} [color=(1,1,1,1)]
* @param {number} [lineWidth=0]
* @param {Color} [lineColor=(0,0,0,1)]
* @param {boolean} [screenSpace=false]
* @param {CanvasRenderingContext2D} [context=mainContext]
* @memberof Draw */
function drawPoly(points, color=new Color, lineWidth=0, lineColor=new Color(0,0,0), screenSpace, context=mainContext)
{
ASSERT(isColor(color) && isColor(lineColor));
context.fillStyle = color.toString();
context.beginPath();
for (const point of screenSpace ? points : points.map(worldToScreen))
context.lineTo(point.x, point.y);
context.closePath();
context.fill();
if (lineWidth)
{
context.strokeStyle = lineColor.toString();
context.lineWidth = screenSpace ? lineWidth : lineWidth*cameraScale;
context.stroke();
}
}
/** Draw colored ellipse using passed in point
* @param {Vector2} pos
* @param {number} [width=1]
* @param {number} [height=1]
* @param {number} [angle=0]
* @param {Color} [color=(1,1,1,1)]
* @param {number} [lineWidth=0]
* @param {Color} [lineColor=(0,0,0,1)]
* @param {boolean} [screenSpace=false]
* @param {CanvasRenderingContext2D} [context=mainContext]
* @memberof Draw */
function drawEllipse(pos, width=1, height=1, angle=0, color=new Color, lineWidth=0, lineColor=new Color(0,0,0), screenSpace, context=mainContext)
{
ASSERT(isColor(color) && isColor(lineColor));
if (!screenSpace)
{
pos = worldToScreen(pos);
width *= cameraScale;
height *= cameraScale;
lineWidth *= cameraScale;
}
context.fillStyle = color.toString();
context.beginPath();
context.ellipse(pos.x, pos.y, width, height, angle, 0, 9);
context.fill();
if (lineWidth)
{
context.strokeStyle = lineColor.toString();
context.lineWidth = lineWidth;
context.stroke();
}
}
/** Draw colored circle using passed in point
* @param {Vector2} pos
* @param {number} [radius=1]
* @param {Color} [color=(1,1,1,1)]
* @param {number} [lineWidth=0]
* @param {Color} [lineColor=(0,0,0,1)]
* @param {boolean} [screenSpace=false]
* @param {CanvasRenderingContext2D} [context=mainContext]
* @memberof Draw */
function drawCircle(pos, radius=1, color=new Color, lineWidth=0, lineColor=new Color(0,0,0), screenSpace, context=mainContext)
{ drawEllipse(pos, radius, radius, 0, color, lineWidth, lineColor, screenSpace, context); }
/** Draw directly to a 2d canvas context in world space
* @param {Vector2} pos
* @param {Vector2} size
* @param {number} angle
* @param {boolean} mirror
* @param {Function} drawFunction
* @param {boolean} [screenSpace=false]
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context=mainContext]
* @memberof Draw */
function drawCanvas2D(pos, size, angle, mirror, drawFunction, screenSpace, context=mainContext)
{
if (!screenSpace)
{
// transform from world space to screen space
pos = worldToScreen(pos);
size = size.scale(cameraScale);
}
context.save();
context.translate(pos.x+.5, pos.y+.5);
context.rotate(angle);
context.scale(mirror ? -size.x : size.x, -size.y);
drawFunction(context);
context.restore();
}
/** Draw text on main canvas in world space
* Automatically splits new lines into rows
* @param {string} text
* @param {Vector2} pos
* @param {number} [size]
* @param {Color} [color=(1,1,1,1)]
* @param {number} [lineWidth]
* @param {Color} [lineColor=(0,0,0,1)]
* @param {CanvasTextAlign} [textAlign='center']
* @param {string} [font=fontDefault]
* @param {number} [maxWidth]
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context=mainContext]
* @memberof Draw */
function drawText(text, pos, size=1, color, lineWidth=0, lineColor, textAlign, font, maxWidth, context=mainContext)
{
drawTextScreen(text, worldToScreen(pos), size*cameraScale, color, lineWidth*cameraScale, lineColor, textAlign, font, maxWidth, context);
}
/** Draw text on overlay canvas in world space
* Automatically splits new lines into rows
* @param {string} text
* @param {Vector2} pos
* @param {number} [size]
* @param {Color} [color=(1,1,1,1)]
* @param {number} [lineWidth]
* @param {Color} [lineColor=(0,0,0,1)]
* @param {CanvasTextAlign} [textAlign='center']
* @param {string} [font=fontDefault]
* @param {number} [maxWidth]
* @memberof Draw */
function drawTextOverlay(text, pos, size=1, color, lineWidth=0, lineColor, textAlign, font, maxWidth)
{
drawText(text, pos, size, color, lineWidth, lineColor, textAlign, font, maxWidth, overlayContext);
}
/** Draw text on overlay canvas in screen space
* Automatically splits new lines into rows
* @param {string} text
* @param {Vector2} pos
* @param {number} [size]
* @param {Color} [color=(1,1,1,1)]
* @param {number} [lineWidth]
* @param {Color} [lineColor=(0,0,0,1)]
* @param {CanvasTextAlign} [textAlign]
* @param {string} [font=fontDefault]
* @param {number} [maxWidth]
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context=overlayContext]
* @memberof Draw */
function drawTextScreen(text, pos, size=1, color=new Color, lineWidth=0, lineColor=new Color(0,0,0), textAlign='center', font=fontDefault, maxWidth=undefined, context=overlayContext)
{
context.fillStyle = color.toString();
context.lineWidth = lineWidth;
context.strokeStyle = lineColor.toString();
context.textAlign = textAlign;
context.font = size + 'px '+ font;
context.textBaseline = 'middle';
context.lineJoin = 'round';
pos = pos.copy();
const lines = (text+'').split('\n');
pos.y -= (lines.length-1) * size/2; // center text vertically
lines.forEach(line=>
{
lineWidth && context.strokeText(line, pos.x, pos.y, maxWidth);
context.fillText(line, pos.x, pos.y, maxWidth);
pos.y += size;
});
}
/** Enable normal or additive blend mode
* @param {boolean} [additive]
* @param {boolean} [useWebGL=glEnable]
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context=mainContext]
* @memberof Draw */
function setBlendMode(additive, useWebGL=glEnable, context)
{
ASSERT(!context || !useWebGL, 'context only supported in canvas 2D mode');
if (useWebGL)
glAdditive = additive;
else
{
if (!context)
context = mainContext;
context.globalCompositeOperation = additive ? 'lighter' : 'source-over';
}
}
/** Combines all LittleJS canvases onto the main canvas and clears them
* This is necessary for things like saving a screenshot
* @memberof Draw */
function combineCanvases()
{
// combine canvases
glCopyToContext(mainContext, true);
mainContext.drawImage(overlayCanvas, 0, 0);
// clear canvases
glClearCanvas();
overlayCanvas.width |= 0;
}
///////////////////////////////////////////////////////////////////////////////
let engineFontImage;
/**
* Font Image Object - Draw text on a 2D canvas by using characters in an image
* - 96 characters (from space to tilde) are stored in an image
* - Uses a default 8x8 font if none is supplied
* - You can also use fonts from the main tile sheet
* @example
* // use built in font
* const font = new FontImage;
*
* // draw text
* font.drawTextScreen("LittleJS\nHello World!", vec2(200, 50));
*/
class FontImage
{
/** Create an image font
* @param {HTMLImageElement} [image] - Image for the font, if undefined default font is used
* @param {Vector2} [tileSize=(8,8)] - Size of the font source tiles
* @param {Vector2} [paddingSize=(0,1)] - How much extra space to add between characters
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context=overlayContext] - context to draw to
*/
constructor(image, tileSize=vec2(8), paddingSize=vec2(0,1), context=overlayContext)
{
// load default font image
if (!engineFontImage)
(engineFontImage = new Image).src = 'data:image/png;base64,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';
this.image = image || engineFontImage;
this.tileSize = tileSize;
this.paddingSize = paddingSize;
this.context = context;
}
/** Draw text in world space using the image font
* @param {string} text
* @param {Vector2} pos
* @param {number} [scale=.25]
* @param {boolean} [center]
*/
drawText(text, pos, scale=1, center)
{
this.drawTextScreen(text, worldToScreen(pos).floor(), scale*cameraScale|0, center);
}
/** Draw text in screen space using the image font
* @param {string} text
* @param {Vector2} pos
* @param {number} [scale]
* @param {boolean} [center]
*/
drawTextScreen(text, pos, scale=4, center)
{
const context = this.context;
context.save();
const size = this.tileSize;
const drawSize = size.add(this.paddingSize).scale(scale);
const cols = this.image.width / this.tileSize.x |0;
(text+'').split('\n').forEach((line, i)=>
{
const centerOffset = center ? line.length * size.x * scale / 2 |0 : 0;
for(let j=line.length; j--;)
{
// draw each character
let charCode = line[j].charCodeAt(0);
if (charCode < 32 || charCode > 127)
charCode = 127; // unknown character
// get the character source location and draw it
const tile = charCode - 32;
const x = tile % cols;
const y = tile / cols |0;
const drawPos = pos.add(vec2(j,i).multiply(drawSize));
context.drawImage(this.image, x * size.x, y * size.y, size.x, size.y,
drawPos.x - centerOffset, drawPos.y, size.x * scale, size.y * scale);
}
});
context.restore();
}
}
///////////////////////////////////////////////////////////////////////////////
// Display functions
/** Returns true if fullscreen mode is active
* @return {boolean}
* @memberof Draw */
function isFullscreen() { return !!document.fullscreenElement; }
/** Toggle fullscreen mode
* @memberof Draw */
function toggleFullscreen()
{
const rootElement = mainCanvas.parentElement;
if (isFullscreen())
{
if (document.exitFullscreen)
document.exitFullscreen();
}
else if (rootElement.requestFullscreen)
rootElement.requestFullscreen();
}
/** Set the cursor style
* @param {string} cursorStyle - CSS cursor style (auto, none, crosshair, etc)
* @memberof Draw */
function setCursor(cursorStyle = 'auto')
{
const rootElement = mainCanvas.parentElement;
rootElement.style.cursor = cursorStyle;
}