engineDebug.js

/*
    LittleJS - Debug Build
    MIT License - Copyright 2021 Frank Force
*/

/** 
 * LittleJS Debug System
 * <br> - Press ~ to show debug overlay with mouse pick
 * <br> - Number keys toggle debug functions
 * <br> - +/- apply time scale
 * <br> - Debug primitive rendering
 * <br> - Save a 2d canvas as an image
 * @namespace Debug
 */

'use strict';

/** True if debug is enabled
 *  @default
 *  @memberof Debug */
const debug = 1;

/** True if asserts are enaled
 *  @default
 *  @memberof Debug */
const enableAsserts = 1;

/** Size to render debug points by default
 *  @default
 *  @memberof Debug */
const debugPointSize = .5;

/** True if watermark with FPS should be down
 *  @default
 *  @memberof Debug */
let showWatermark = 1;

/** True if god mode is enabled, handle this however you want
 *  @default
 *  @memberof Debug */
let godMode = 0;

// Engine internal variables not exposed to documentation
let debugPrimitives = [], debugOverlay = 0, debugPhysics = 0, debugRaycast = 0,
debugParticles = 0, debugGamepads = 0, debugMedals = 0, debugTakeScreenshot, downloadLink;

///////////////////////////////////////////////////////////////////////////////
// Debug helper functions

/** Asserts if the experssion is false, does not do anything in release builds
 *  @param {Boolean} assertion
 *  @param {Object}  output
 *  @memberof Debug */
const ASSERT = enableAsserts ? (...assert)=> console.assert(...assert) : ()=>{};

/** Draw a debug rectangle in world space
 *  @param {Vector2} pos
 *  @param {Vector2} [size=new Vector2()]
 *  @param {String}  [color='#fff']
 *  @param {Number}  [time=0]
 *  @param {Number}  [angle=0]
 *  @param {Boolean} [fill=0]
 *  @memberof Debug */
const debugRect = (pos, size=vec2(), color='#fff', time=0, angle=0, fill=0)=> 
{
    ASSERT(typeof color == 'string'); // pass in regular html strings as colors
    debugPrimitives.push({pos, size:vec2(size), color, time:new Timer(time), angle, fill});
}

/** Draw a debug circle in world space
 *  @param {Vector2} pos
 *  @param {Number}  [radius=0]
 *  @param {String}  [color='#fff']
 *  @param {Number}  [time=0]
 *  @param {Boolean} [fill=0]
 *  @memberof Debug */
const debugCircle = (pos, radius=0, color='#fff', time=0, fill=0)=>
{
    ASSERT(typeof color == 'string'); // pass in regular html strings as colors
    debugPrimitives.push({pos, size:radius, color, time:new Timer(time), angle:0, fill});
}

/** Draw a debug point in world space
 *  @param {Vector2} pos
 *  @param {String}  [color='#fff']
 *  @param {Number}  [time=0]
 *  @param {Number}  [angle=0]
 *  @memberof Debug */
const debugPoint = (pos, color, time, angle)=> debugRect(pos, 0, color, time, angle);

/** Draw a debug line in world space
 *  @param {Vector2} posA
 *  @param {Vector2} posB
 *  @param {String}  [color='#fff']
 *  @param {Number}  [thickness=.1]
 *  @param {Number}  [time=0]
 *  @memberof Debug */
const debugLine = (posA, posB, color, thickness=.1, time)=>
{
    const halfDelta = vec2((posB.x - posA.x)/2, (posB.y - posA.y)/2);
    const size = vec2(thickness, halfDelta.length()*2);
    debugRect(posA.add(halfDelta), size, color, time, halfDelta.angle(), 1);
}

/** Draw a debug axis aligned bounding box in world space
 *  @param {Vector2} posA
 *  @param {Vector2} sizeA
 *  @param {Vector2} posB
 *  @param {Vector2} sizeB
 *  @param {String}  [color='#fff']
 *  @memberof Debug */
const debugAABB = (pA, sA, pB, sB, color)=>
{
    const minPos = vec2(min(pA.x - sA.x/2, pB.x - sB.x/2), min(pA.y - sA.y/2, pB.y - sB.y/2));
    const maxPos = vec2(max(pA.x + sA.x/2, pB.x + sB.x/2), max(pA.y + sA.y/2, pB.y + sB.y/2));
    debugRect(minPos.lerp(maxPos,.5), maxPos.subtract(minPos), color);
}

/** Draw a debug axis aligned bounding box in world space
 *  @param {String}  text
 *  @param {Vector2} pos
 *  @param {Number}  [size=1]
 *  @param {String}  [color='#fff']
 *  @param {Number}  [time=0]
 *  @param {Number}  [angle=0]
 *  @param {String}  [font='monospace']
 *  @memberof Debug */
const debugText = (text, pos, size=1, color='#fff', time=0, angle=0, font='monospace')=> 
{
    ASSERT(typeof color == 'string'); // pass in regular html strings as colors
    debugPrimitives.push({text, pos, size, color, time:new Timer(time), angle, font});
}

/** Clear all debug primitives in the list
 *  @memberof Debug */
const debugClear = ()=> debugPrimitives = [];

/** Save a canvas to disk 
 *  @param {HTMLCanvasElement} canvas
 *  @param {String}            [filename]
 *  @memberof Debug */
const debugSaveCanvas = (canvas, filename = engineName + '.png') =>
{
    downloadLink.download = 'screenshot.png';
    downloadLink.href = canvas.toDataURL('image/png').replace('image/png','image/octet-stream');
    downloadLink.click();
}

///////////////////////////////////////////////////////////////////////////////
// Engine debug function (called automatically)

const debugInit = ()=>
{
    // create link for saving screenshots
    document.body.appendChild(downloadLink = document.createElement('a'));
    downloadLink.style.display = 'none';
}

const debugUpdate = ()=>
{
    if (!debug)
        return;

    if (keyWasPressed(192)) // ~
        debugOverlay = !debugOverlay;
    if (debugOverlay)
    {
        if (keyWasPressed(48)) // 0
            showWatermark = !showWatermark;
        if (keyWasPressed(49)) // 1
            debugPhysics = !debugPhysics, debugParticles = 0;
        if (keyWasPressed(50)) // 2
            debugParticles = !debugParticles, debugPhysics = 0;
        if (keyWasPressed(51)) // 3
            debugGamepads = !debugGamepads;
        if (keyWasPressed(52)) // 4
            godMode = !godMode;
        if (keyWasPressed(53)) // 5
            debugTakeScreenshot = 1;
        //if (keyWasPressed(54)) // 6
        //if (keyWasPressed(55)) // 7
        //if (keyWasPressed(56)) // 8
        //if (keyWasPressed(57)) // 9
    }
}

const debugRender = ()=>
{
    glCopyToContext(mainContext);

    if (debugTakeScreenshot)
    {
        // composite canvas
        glCopyToContext(mainContext, 1);
        mainContext.drawImage(overlayCanvas, 0, 0);
        overlayCanvas.width |= 0;

        debugSaveCanvas(mainCanvas);
        debugTakeScreenshot = 0;
    }

    if (debugGamepads && gamepadsEnable && navigator.getGamepads)
    {
        // gamepad debug display
        const gamepads = navigator.getGamepads();
        for (let i = gamepads.length; i--;)
        {
            const gamepad = gamepads[i];
            if (gamepad)
            {
                const stickScale = 1;
                const buttonScale = .2;
                const centerPos = cameraPos;
                const sticks = stickData[i];
                for (let j = sticks.length; j--;)
                {
                    const drawPos = centerPos.add(vec2(j*stickScale*2, i*stickScale*3));
                    const stickPos = drawPos.add(sticks[j].scale(stickScale));
                    debugCircle(drawPos, stickScale, '#fff7',0,1);
                    debugLine(drawPos, stickPos, '#f00');
                    debugPoint(stickPos, '#f00');
                }
                for (let j = gamepad.buttons.length; j--;)
                {
                    const drawPos = centerPos.add(vec2(j*buttonScale*2, i*stickScale*3-stickScale-buttonScale));
                    const pressed = gamepad.buttons[j].pressed;
                    debugCircle(drawPos, buttonScale, pressed ? '#f00' : '#fff7', 0, 1);
                    debugText(j, drawPos, .2);
                }
            }
        }
    }

    if (debugOverlay)
    {
        // mouse pick
        let bestDistance = Infinity, bestObject;
        for (const o of engineObjects)
        {
            if (o.canvas || o.destroyed)
                continue; // skip tile layers

            const size = o.size.copy();
            if (!size.x || !size.y)
                continue;

            const distance = mousePos.distanceSquared(o.pos);
            if (distance < bestDistance)
            {
                bestDistance = distance;
                bestObject = o
            }

            // show object info
            const color = new Color(
                o.collideTiles?1:0, 
                o.collideSolidObjects?1:0,
                o.isSolid?1:0, 
                o.parent ? .2 : .5);
            size.x = max(size.x, .2);
            size.y = max(size.y, .2);
            drawRect(o.pos, size, color);
            drawRect(o.pos, size.scale(.8), o.parent ? new Color(1,1,1,.5) : new Color(0,0,0,.8));
            o.parent && drawLine(o.pos, o.parent.pos, .1, new Color(0,0,1,.5));
        }
        
        if (bestObject)
        {
            const saveContext = mainContext;
            mainContext = overlayContext
            const raycastHitPos = tileCollisionRaycast(bestObject.pos, mousePos);
            raycastHitPos && drawRect(raycastHitPos.floor().add(vec2(.5)), vec2(1), new Color(0,1,1,.3));
            drawRect(mousePos.floor().add(vec2(.5)), vec2(1), new Color(0,0,1,.5));
            drawLine(mousePos, bestObject.pos, .1, !raycastHitPos ? new Color(0,1,0,.5) : new Color(1,0,0,.5));

            const debugText = 'mouse pos = ' + mousePos + 
                '\nmouse collision = ' + getTileCollisionData(mousePos) + 
                '\n\n--- object info ---\n' +
                bestObject.toString();
            drawTextScreen(debugText, mousePosScreen, 24, new Color, .05, undefined, undefined, 'monospace');
            mainContext = saveContext;
        }

        glCopyToContext(mainContext);
    }

    {
        // draw debug primitives
        overlayContext.lineWidth = 2;
        const pointSize = debugPointSize * cameraScale;
        debugPrimitives.forEach(p=>
        {
            overlayContext.save();

            // create canvas transform from world space to screen space
            const pos = worldToScreen(p.pos);
            
            overlayContext.translate(pos.x|0, pos.y|0);
            overlayContext.rotate(p.angle);
            overlayContext.fillStyle = overlayContext.strokeStyle = p.color;

            if (p.text != undefined)
            {
                overlayContext.font = p.size*cameraScale + 'px '+ p.font;
                overlayContext.textAlign = 'center';
                overlayContext.textBaseline = 'middle';
                overlayContext.fillText(p.text, 0, 0);
            }
            else if (p.size == 0 || p.size.x === 0 && p.size.y === 0 )
            {
                // point
                overlayContext.fillRect(-pointSize/2, -1, pointSize, 3);
                overlayContext.fillRect(-1, -pointSize/2, 3, pointSize);
            }
            else if (p.size.x != undefined)
            {
                // rect
                const w = p.size.x*cameraScale|0, h = p.size.y*cameraScale|0;
                p.fill && overlayContext.fillRect(-w/2|0, -h/2|0, w, h);
                overlayContext.strokeRect(-w/2|0, -h/2|0, w, h);
            }
            else
            {
                // circle
                overlayContext.beginPath();
                overlayContext.arc(0, 0, p.size*cameraScale, 0, 9);
                p.fill && overlayContext.fill();
                overlayContext.stroke();
            }
            
            overlayContext.restore();
        });

        // remove expired pritives
        debugPrimitives = debugPrimitives.filter(r=>r.time.get()<0);
    }

    {
        // draw debug overlay
        overlayContext.save();
        overlayContext.fillStyle = '#fff';
        overlayContext.textAlign = 'left';
        overlayContext.textBaseline = 'top';
        overlayContext.font = '28px monospace';
        overlayContext.shadowColor = '#000';
        overlayContext.shadowBlur = 9;

        let x = 9, y = -20, h = 30;
        if (debugOverlay)
        {
            overlayContext.fillText(engineName, x, y += h);
            overlayContext.fillText('Objects: ' + engineObjects.length, x, y += h);
            overlayContext.fillText('Time: ' + formatTime(time), x, y += h);
            overlayContext.fillText('---------', x, y += h);
            overlayContext.fillStyle = '#f00';
            overlayContext.fillText('~: Debug Overlay', x, y += h);
            overlayContext.fillStyle = debugPhysics ? '#f00' : '#fff';
            overlayContext.fillText('1: Debug Physics', x, y += h);
            overlayContext.fillStyle = debugParticles ? '#f00' : '#fff';
            overlayContext.fillText('2: Debug Particles', x, y += h);
            overlayContext.fillStyle = debugGamepads ? '#f00' : '#fff';
            overlayContext.fillText('3: Debug Gamepads', x, y += h);
            overlayContext.fillStyle = godMode ? '#f00' : '#fff';
            overlayContext.fillText('4: God Mode', x, y += h);
            overlayContext.fillStyle = '#fff';
            overlayContext.fillText('5: Save Screenshot', x, y += h);

            let keysPressed = '';
            for(const i in inputData[0])
            {
                if (i && keyIsDown(i, 0))
                    keysPressed += i + ' ' ;
            }
            keysPressed && overlayContext.fillText('Keys Down: ' + keysPressed, x, y += h);

            let buttonsPressed = '';
            if (inputData[1])
            for(const i in inputData[1])
            {
                if (i && keyIsDown(i, 1))
                    buttonsPressed += i + ' ' ;
            }
            buttonsPressed && overlayContext.fillText('Gamepad: ' + buttonsPressed, x, y += h);
        }
        else
        {
            overlayContext.fillText(debugPhysics ? 'Debug Physics' : '', x, y += h);
            overlayContext.fillText(debugParticles ? 'Debug Particles' : '', x, y += h);
            overlayContext.fillText(godMode ? 'God Mode' : '', x, y += h);
            overlayContext.fillText(debugGamepads ? 'Debug Gamepads' : '', x, y += h);
        }
    
        overlayContext.restore();
    }
}