Add new backgrounds (#764)

* Add quark background

* add galaxy background

parts/backgrounds/galaxy.lua

@@ -0,0 +1,43 @@
+--Space with stars
+local gc=love.graphics
+local circle,setColor,hsv=gc.circle,gc.setColor,COLOR.hsv
+local rnd,pi,sin,cos=math.random,math.pi,math.sin,math.cos
+local back={}
+
+local sDist,sRev={},{} -- star data in SoA [distance from center, revolution progress, color]
+local k
+
+local d,r -- temp vars for optimization
+function back.init()
+    if sDist[1]then return end
+    local max
+    for i=0,20 do
+        max=16*(i+1)
+        for j=1,max do
+            sDist[#sDist+1]=i+rnd()
+            sRev[#sRev+1]=2*pi*j/max+2*pi*rnd()/max
+        end
+    end
+end
+function back.resize(w,h)k=3*SCR.k end
+function back.update(dt)
+    for i=1,#sDist do sRev[i]=(sRev[i]+dt/(sDist[i]+1))%(2*pi) end
+end
+function back.draw()
+    gc.clear()
+    gc.translate(SCR.cx,SCR.cy)
+    gc.rotate(1)
+    for i=1,#sDist do
+        d,r=sDist[i],sRev[i]
+        if d<5 then
+            setColor(hsv(.088,(d-2)/7,1,.7))
+        else
+            setColor(hsv(.572,d/70+.1,(22-d)/12,.7))
+        end
+        circle('fill',8*d*cos(r),24*d*sin(r),3)
+    end
+    gc.rotate(-1)
+    gc.translate(-SCR.cx,-SCR.cy)
+end
+function back.discard()end
+return back

parts/backgrounds/quarks.lua

@@ -0,0 +1,150 @@
+local gc=love.graphics
+local hsv=COLOR.hsv
+local circle,push,pop,rot,translate,setColor=gc.circle,gc.push,gc.pop,gc.rotate,gc.translate,gc.setColor
+local rnd,sin,cos,twopi,pow,log,ceil=math.random,math.sin,math.cos,2*math.pi,math.pow,math.log,math.ceil
+local back={}
+
+local qX,qY,qdX,qdY={},{},{},{} -- quark data in SoA [size, X, Y, dx, dy, color]
+local colors={{1,0,0,.8},{0,1,0,.8},{0,0,1,.8}}
+
+local ptcclr={{1,0,0},{0,1,0},{0,0,1}}
+local apcclr={{0,1,1},{1,0,1},{1,1,0}}
+
+local blasts={} -- data about annihilation blasts from particles and antiparticles colliding
+local ptc={} -- particle-antiparticle data (antiparticle is a mirror of particle)
+local nextpair=math.huge
+
+local W,H,size
+local quarkCount=400
+
+local theta,side,x,y,t,p,cutoff -- temp vars for optimization
+local function spawnQuarkRandom(i)
+    qX[i]=rnd(W)-10             -- X
+    qY[i]=rnd(H)-10             -- Y
+    theta=rnd()*twopi
+    qdX[i]=cos(theta)*300   -- dx
+    qdY[i]=sin(theta)*300   -- dy
+end
+local function spawnQuarkEdge(i)
+    side=rnd(4)
+    if side==1 then -- Up edge of screen
+        qX[i]=rnd(SCR.x-10,SCR.ex+10)
+        qY[i]=SCR.y-10
+    elseif side==2 then -- Right edge of screen
+        qX[i]=SCR.ex+10
+        qY[i]=rnd(SCR.y-10,SCR.ey+10)
+    elseif side==3 then -- Down edge of screen
+        qX[i]=rnd(SCR.x-10,SCR.ex+10)
+        qY[i]=SCR.ey+10
+    elseif side==4 then -- Left edge of screen
+        qX[i]=SCR.x-10
+        qY[i]=rnd(SCR.y-10,SCR.ey+10)
+    end
+    theta=rnd()*twopi
+    qdX[i]=cos(theta)*300   -- dx
+    qdY[i]=sin(theta)*300   -- dy
+end
+local function spawnParticlePair()
+    x,y=rnd(W)-10,rnd(H)-10
+    theta=rnd()*twopi
+    ptc[#ptc+1]={x=x,y=y,dist=0,theta=theta,v=500, c=rnd(3)}
+end
+local function spawnBlast(_x,_y)blasts[#blasts+1]={x=_x,y=_y,t=0}end
+
+function back.init()
+    qX,qY,qdX,qdY={},{},{},{}
+    blasts={}
+    ptc={}
+    cutoff={ceil(quarkCount/3),ceil(2*quarkCount/3)}
+    BG.resize(SCR.w,SCR.h)
+end
+function back.resize(w,h)
+    W,H=w+20,h+20
+    for i=1,quarkCount do spawnQuarkRandom(i)end
+    size=2.6*SCR.k
+end
+function back.update(dt)
+    local debug_dt=TIME()
+    --Move far-away quarks
+    for i=1,quarkCount do
+        qX[i]=qX[i]+qdX[i]*dt
+        qY[i]=qY[i]+qdY[i]*dt
+        if qX[i]<SCR.x-26 or qX[i]>SCR.ex+26 or qY[i]<SCR.y-26 or qY[i]>SCR.ey+26 then spawnQuarkEdge(i)end
+    end
+
+    --Particle pair attraction & destruction
+    for i=1,#ptc do
+        p=ptc[i]
+        if not p then goto continue end
+        p.dist=p.dist+p.v*dt
+
+        p.v=p.v-pow(p.dist,2)*dt
+
+        --Destroy colliding particle pairs
+        if p.dist<=10 and p.v<=0 then
+            spawnBlast(p.x,p.y)
+            for j=i,#ptc do ptc[j]=ptc[j+1]end
+            i=i-1
+        end
+        ::continue::
+    end
+
+    --Age blasts, delete old blasts
+    for i=1,#blasts do
+        if not blasts[i]then goto continue end
+        blasts[i].t=blasts[i].t+dt
+
+        if blasts[i].t>=1 then
+            for j=i,#blasts do
+                blasts[j]=blasts[j+1]
+            end
+            i=i-1
+        end
+        ::continue::
+    end
+
+    --Spawn particle pairs
+    nextpair=nextpair-dt
+    if nextpair==math.huge then
+        nextpair=rnd()+rnd(0,3)
+    elseif nextpair<=0 then
+        spawnParticlePair()
+        nextpair=rnd()+rnd(0,3)
+    end
+end
+function back.draw()
+    local debug_dt=TIME()
+    gc.clear(0.08,0.04,0.01)
+    translate(-10,-10)
+    setColor(1,0,0,.8)
+    for i=1,cutoff[1]do circle('fill',qX[i],qY[i],size)end -- draw red quarks
+    setColor(0,1,0,.8)
+    for i=cutoff[1]+1,cutoff[2]do circle('fill',qX[i],qY[i],size)end -- draw green quarks
+    setColor(0,0,1,.8)
+    for i=cutoff[2]+1,quarkCount do circle('fill',qX[i],qY[i],size) end -- draw blue quarks
+    for i=1,#ptc do
+        p=ptc[i]
+        push()
+            translate(p.x,p.y)rot(p.theta)
+
+            setColor(ptcclr[p.c])
+            circle('fill', p.dist,0,4*size)
+            setColor(apcclr[p.c])
+            circle('fill',-p.dist,0,4*size)
+        pop()
+    end
+    for i=1,#blasts do
+        t=blasts[i].t
+        setColor(hsv(-80*t,1-1.7*log(5*t,10),1,1-t))
+        circle('fill',blasts[i].x,blasts[i].y,40*log(3*t+1.7,3))
+    end
+    translate(10,10)
+end
+function back.discard()
+    qX,qY,qdX,qdY,qC=nil,nil,nil,nil,nil
+    blasts=nil
+    ptc=nil
+    nextpair=math.huge
+    collectgarbage('collect')
+end
+return back