Planets shader for Corona

_readme.md

#Corona planet shader v0.1#

###Instructions###

1. Download and unpack this gist into folder
2. Add this assets two images and name them "red.jpg" and "[blue.jpg] (http://i.imgur.com/V3Tw97g.jpg)" in same folder (you will have to download and rename them)
3. Open project in Corona Simulator 🤘
4. [OPTIONAL]Works best with retina/hi-dpi screens

####WARNING#### This shader is very computationally expensive and slow.

build.settings

--
-- For more information on build.settings see the Corona SDK Build Guide at:
-- http://docs.coronalabs.com/guide/distribution/buildSettings/index.html
--

settings =
{
	
	orientation =
	{
		-- Supported values for orientation:
		-- portrait, portraitUpsideDown, landscapeLeft, landscapeRight

		default = "landscapeRight",
		supported = { "landscapeRight", }
	},
	
	excludeFiles =
	{
		-- Include only the necessary icon files on each platform
		iphone = { "Icon-*dpi.png", },
		android = { "Icon.png", "Icon-Small-*.png", "Icon*@2x.png", },
	},

	--
	-- iOS Section
	--
	iphone =
	{
		plist =
		{
			UIStatusBarHidden = false,
			UIPrerenderedIcon = true, -- set to false for "shine" overlay
			--UIApplicationExitsOnSuspend = true, -- uncomment to quit app on suspend

			CFBundleIconFiles =
			{
				"Icon.png",
				"Icon@2x.png",
				"Icon-60.png",
				"Icon-60@2x.png",
				"Icon-60@3x.png",
				"Icon-72.png",
				"Icon-72@2x.png",
				"Icon-76.png",
				"Icon-76@2x.png",
				"Icon-Small.png",
				"Icon-Small@2x.png",
				"Icon-Small@3x.png",
				"Icon-Small-40.png",
				"Icon-Small-40@2x.png",
				"Icon-Small-50.png",
				"Icon-Small-50@2x.png",
			},

			--[[
			-- iOS app URL schemes:
			CFBundleURLTypes =
			{
				{
					CFBundleURLSchemes =
					{
						"fbXXXXXXXXX",  -- replace XXXXXXXXX with your Facebook appId
					}
				}
			}
			--]]
		}
	},
	
	--
	-- Android Section
	--
	android =
	{
		usesPermissions =
		{
			"android.permission.INTERNET",
		},
	},
}

config.lua

application =
{

	content =
	{
		width = 768,
		height = 1024, 
		scale = "adaptive",
		fps = 30,
		
		--[[
		imageSuffix =
		{
			    ["@2x"] = 2,
		},
		--]]
	},

	--[[
	-- Push notifications
	notification =
	{
		iphone =
		{
			types =
			{
				"badge", "sound", "alert", "newsstand"
			}
		}
	},
	--]]    
}

kernel_composite_planet.lua

local kernel = {}

kernel.language = "glsl"

kernel.category = "filter"

kernel.name = "planet"

kernel.isTimeDependent = true

kernel.vertexData =
{
	{
		name = "vx", -- horizontal "rotation" speed
		default = 0.1, 
		min = -2,
		max = 2,
		index = 0, -- This corresponds to CoronaVertexUserData.x
	},
	{
		name = "vy", -- vertical "rotation" speed
		default = 0, 
		min = -2,
		max = 2,
		index = 1, -- This corresponds to CoronaVertexUserData.y
	},
	{
		name = "t0", -- Time offset from start time
		default = 0, 
		min = -1000,
		max = 1000,
		index = 2, -- This corresponds to CoronaVertexUserData.z
	},
}

kernel.fragment =
[[
P_COLOR vec4 FragmentKernel( P_UV vec2 uv )
{
	P_UV vec4 fragColor; //return value

	P_UV  vec2 p = -1.0 + 2.0 * uv;
	//p is now vector from center of texture, pointing to this texel
	P_UV float r = dot(p, p);
	
	if (r<=1.0) {
		P_UV vec2 Velocity = CoronaVertexUserData.xy;
		P_UV float f;
		if(r>=0.00001) {
	   		 f = (1.0 - sqrt(1.00 - r)) / r;
	   	}else
	   	{
	   		 f = 1.0-r/2.0;
		}
   		P_UV  vec2 uv1;
   		uv1.x = 1.0*p.x*f;
		uv1.y = 1.0*p.y*f;
        
		P_UV float z1 = sqrt(1.0 - uv1.x*uv1.x-uv1.y*uv1.y);
        P_UV float z2 = distance( vec2(0.7,0.7), uv1);

		uv1 += (CoronaTotalTime+CoronaVertexUserData.z)*Velocity;
   		
		fragColor = vec4(texture2D(CoronaSampler0, uv1).rgb*z2, 1.0*z1);
	} else {
		fragColor = vec4(0.0,0.0,0.0, 0.0);
	}
	return CoronaColorScale(fragColor);
}
]]

return kernel

main.lua

display.setDefault( "textureWrapX", "mirroredRepeat" )
display.setDefault( "textureWrapY", "mirroredRepeat" )



display.setDefault( 'isShaderCompilerVerbose', true )
local kernel = require("kernel_composite_planet")
graphics.defineEffect( kernel )

function setPlanet( o, planet )
	local paint =
	{
		type="image",
		filename=planet
	}

	o.fill = paint
	o.fill.effect = "filter.custom.planet"
	o.fill.effect.vx = 0.1 - math.random()*0.2
	o.fill.effect.vy = 0.1 - math.random()*0.2
	o.fill.effect.t0 = math.random( 2, 50 )
end


local cy = display.contentCenterY
local w = display.contentWidth;
local sz = math.min(w/2.1,cy*2)

local object1 = display.newRect( w/4, cy, sz, sz )
local object2 = display.newRect( w*3/4, cy, sz, sz )

setPlanet(object1, "blue.jpg")
setPlanet(object2, "red.jpg")


-- object1:setFillColor( 1, 0,0,0.5 )  -- uncomment after global worming

Nice, and an interesting solution to the north / south poles problem. (I've been playing with a sphere myself but just sort of ignore it...)

Did you compare the "fragColor = vec4(0.0,0.0,0.0, 0.0);" against "discard;" at all? Just curious since I don't have much hardware handy to make decent comparisons.