Smoke puff

gistfile1.txt

-- flak

function setup()      
    shellbursts={} 
    counter=0
    nextExplosion=math.random()*2+1
end

function draw()
    nextExplosion=nextExplosion-DeltaTime
    if nextExplosion<0 then 
        local s=Smoke(vec2(math.random(100,700),math.random(400,700)),256*(.25+.75*math.random()),2,7)
        table.insert(shellbursts,s)
        nextExplosion=math.random()*5+2
    end
    background(117, 154, 181, 255)
    for i,s in pairs(shellbursts) do
        if s:draw()==false then table.remove(shellbursts,i) end
    end
end


Smoke=class()

Smoke.img=nil

function Smoke:init(pos,size,explodeSecs,fadeSecs)
    self.pos=pos
    if Smoke.img==nil then Smoke.createImage(512) end 
    self.f={frac=0,fade=1}
    local t1=tween(explodeSecs,self.f,{frac=1},{ easing = tween.easing.quadOut } )
    local t2=tween(fadeSecs,self.f,{fade=0},{ easing = tween.easing.linear } )
    tween.sequence(t1,t2)
    self.m=mesh()
    self.m.texture=Smoke.img
    local w=Smoke.img.width
    local x1,y1,x2,y2=-size/2,-size/2,size/2,size/2
    local tx1,ty1=math.random()*(1-size/w),math.random()*(1-size/w)
    local tx2,ty2=tx1+size/w,ty1+size/w
    v,t={},{}
    v[1]=vec2(x1,y1) t[1]=vec2(tx1,ty1)
    v[2]=vec2(x2,y1) t[2]=vec2(tx2,ty1)
    v[3]=vec2(x2,y2) t[3]=vec2(tx2,ty2)
    v[4]=vec2(x1,y2) t[4]=vec2(tx1,ty2)
    v[5]=vec2(x1,y1) t[5]=vec2(tx1,ty1)
    v[6]=vec2(x2,y2) t[6]=vec2(tx2,ty2)
    self.m.vertices=v
    self.m.texCoords=t
    self.m:setColors(color(255))  
    self.m.shader=shader(smokeShader.vertexShader,smokeShader.fragmentShader) 
    self.m.shader.frac=self.f.frac
    self.m.shader.fade=self.f.fade
    self.m.shader.size=size/w
    self.m.shader.centre=vec2((tx1+tx2)/2,(ty1+ty2)/2)
    self.timer=0
end

function Smoke:draw()
    self.m.shader.frac=self.f.frac
    self.m.shader.fade=self.f.fade
    pushMatrix()
    translate(self.pos.x,self.pos.y)
    self.m:draw()
    popMatrix()
    if self.f.fade>0 then return true else return false end
end

function Smoke.createImage(size)   
    local min,max=100,255
    local m=hmap.create(size,size,0.3)
    local z1,z2=0,0
    for i=0,m.w do
        for j=0,m.h do
            z1=math.min(z1,m[i][j])
            z2=math.max(z2,m[i][j])
        end
    end   
    local img=image(m.w,m.h)  
    local f=(max-min)/(z2-z1)
    for i=1,m.w do
        for j=1,m.h do
            local intensity=min+f*(m[i][j]-z1)
            img:set(i,j,color(intensity))
        end
    end 
    Smoke.img=img  
end