Heat haze example

kernel_filter_custom_heat.lua

--- Heat haze shader.

--
-- Permission is hereby granted, free of charge, to any person obtaining
-- a copy of this software and associated documentation files (the
-- "Software"), to deal in the Software without restriction, including
-- without limitation the rights to use, copy, modify, merge, publish,
-- distribute, sublicense, and/or sell copies of the Software, and to
-- permit persons to whom the Software is furnished to do so, subject to
-- the following conditions:
--
-- The above copyright notice and this permission notice shall be
-- included in all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-- EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-- MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-- IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-- CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-- TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-- SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--
-- [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
--

local kernel = {}

kernel.language = "glsl"

kernel.category = "filter"

-- By default, the group is "custom"
-- kernel.group = "custom"

kernel.name = "heat"

kernel.isTimeDependent = true

-- Expose effect parameters using vertex data
kernel.vertexData =
{
	{
		name = "extend", -- The property name exposed to Lua
		default = 5, 
		min = .25,
		max = 250,
		index = 0, -- This corresponds to CoronaVertexUserData.x
	},

	{
		name = "frequency", -- The property name exposed to Lua
		default = 1.3, 
		min = .2,
		max = 8,
		index = 1, -- This corresponds to CoronaVertexUserData.y
	},

	{
		name = "center", -- The property name exposed to Lua
		default = display.contentCenterX, 
		min = 0,
		max = display.contentWidth,
		index = 2, -- This corresponds to CoronaVertexUserData.2
	}
}

kernel.vertex = [[
	varying P_UV vec2 extension_frac; // Custom varying variable (x = extension, y = fraction)

	P_POSITION vec2 VertexKernel( P_POSITION vec2 position )
	{
		P_DEFAULT float offset = position.x - CoronaVertexUserData.z;
		P_DEFAULT float extend = sign(offset) * CoronaVertexUserData.x;

		extension_frac.x = .5 * extend / (offset + extend);
		extension_frac.y = (offset + 2. * extend) / (offset + extend);

		position.x += extend;

		return position;
	}
]]

kernel.fragment = [[
	#ifdef GL_ES
		precision mediump float;
	#endif

	varying P_UV vec2 extension_frac; // Custom varying variable (x = extension, y = fraction)

	P_COLOR vec4 FragmentKernel( P_UV vec2 texCoord )
	{
		texCoord.x *= extension_frac.y;
		texCoord.x -= extension_frac.x;
	
		P_UV float amp = sin(2. * 3.14159 * (texCoord.y + CoronaTotalTime) * CoronaVertexUserData.y);

		texCoord.x += amp * extension_frac.x;

		if (abs(texCoord.x - .5) > .5) discard;
// P_UV float scale = ceil(.5 - abs(texCoord.x - .5)); // ... failed experiment to use alpha in lieu of discard
		P_COLOR vec4 tcolor = texture2D( CoronaSampler0, texCoord );
// tcolor.a *= scale;
		return CoronaColorScale(tcolor);
	}
]]

return kernel

kernel_filter_custom_heat_no_discard.lua

--- Non-discarding heat haze shader.

--
-- Permission is hereby granted, free of charge, to any person obtaining
-- a copy of this software and associated documentation files (the
-- "Software"), to deal in the Software without restriction, including
-- without limitation the rights to use, copy, modify, merge, publish,
-- distribute, sublicense, and/or sell copies of the Software, and to
-- permit persons to whom the Software is furnished to do so, subject to
-- the following conditions:
--
-- The above copyright notice and this permission notice shall be
-- included in all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-- EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-- MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-- IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-- CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-- TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-- SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--
-- [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
--

local kernel = {}

kernel.language = "glsl"

kernel.category = "filter"

-- By default, the group is "custom"
-- kernel.group = "custom"

kernel.name = "heat_no_discard"

kernel.isTimeDependent = true

-- Expose effect parameters using vertex data
kernel.vertexData =
{
	{
		name = "extend", -- The property name exposed to Lua
		default = 5, 
		min = .25,
		max = 250,
		index = 0, -- This corresponds to CoronaVertexUserData.x
	},

	{
		name = "frequency", -- The property name exposed to Lua
		default = 1.3, 
		min = .2,
		max = 8,
		index = 1, -- This corresponds to CoronaVertexUserData.y
	},

	{
		name = "center", -- The property name exposed to Lua
		default = display.contentCenterX, 
		min = 0,
		max = display.contentWidth,
		index = 2, -- This corresponds to CoronaVertexUserData.2
	}
}

kernel.vertex = [[
	varying P_UV vec2 extension_frac; // Custom varying variable (x = extension, y = fraction)

	P_POSITION vec2 VertexKernel( P_POSITION vec2 position )
	{
		P_DEFAULT float offset = position.x - CoronaVertexUserData.z;
		P_DEFAULT float extend = sign(offset) * CoronaVertexUserData.x;

		extension_frac.x = .5 * extend / (offset + extend);
		extension_frac.y = (offset + 2. * extend) / (offset + extend);

		position.x += extend;

		return position;
	}
]]

kernel.fragment = [[
	#ifdef GL_ES
		precision mediump float;
	#endif

	varying P_UV vec2 extension_frac; // Custom varying variable (x = extension, y = fraction)

	P_COLOR vec4 FragmentKernel( P_UV vec2 texCoord )
	{
		texCoord.x *= extension_frac.y;
		texCoord.x -= extension_frac.x;
	
		P_UV float amp = sin(2. * 3.14159 * (texCoord.y + CoronaTotalTime) * CoronaVertexUserData.y);

		texCoord.x += amp * extension_frac.x;

		P_COLOR vec4 tcolor = texture2D( CoronaSampler0, texCoord );

		return CoronaColorScale(tcolor);
	}
]]

return kernel

main.lua

--- Driver for shader demo.

--
-- Permission is hereby granted, free of charge, to any person obtaining
-- a copy of this software and associated documentation files (the
-- "Software"), to deal in the Software without restriction, including
-- without limitation the rights to use, copy, modify, merge, publish,
-- distribute, sublicense, and/or sell copies of the Software, and to
-- permit persons to whom the Software is furnished to do so, subject to
-- the following conditions:
--
-- The above copyright notice and this permission notice shall be
-- included in all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-- EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-- MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-- IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-- CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-- TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-- SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--
-- [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
--

-- Modules --
local utils = require("utils")

-- Setup
display.setStatusBar( display.HiddenStatusBar )

-- Log compiler errors found in shader code to console
display.setDefault( 'isShaderCompilerVerbose', true )

local cx, cy, CurrentGroup = display.contentCenterX, display.contentCenterY

-- Effect 1 --
local Normal = utils.LoadKernel("filter.custom.heat", function(group, name)
	local image = display.newImageRect(group, "Image1.jpg", 256, 256)

	image.x, image.y = cx, cy
	image.fill.effect = name

	-- Add some controls.
	utils.SliderAndText(image, 10, "extend", .25, 250)
	utils.SliderAndText(image, 40, "frequency", .2, 8)
end)

-- Effect 2 --
local Snapshot = utils.LoadKernel("filter.custom.heat", function(group, name)
	local snap = display.newSnapshot(300, 300)

	group:insert(snap)

	snap.x, snap.y = cx, cy

	-- Put some stuff in the snapshot.
	local red = display.newRect(snap.group, 80 - cx, 90 - cy, 100, 200)

	red:setFillColor(1, 0, 0)

	local BlueY = 250 - cy

	local blue = display.newRect(snap.group, 160 - cx, BlueY, 100, 200)

	blue:setFillColor(0, 0, 1)

	local green = display.newRect(snap.group, 140 - cx, 210 - cy, 200, 100)

	green:setFillColor(0, 1, 0)

	-- Add some controls.
	snap.fill.effect = name

	utils.SliderAndText(snap, 10, "extend", .25, 250)
	utils.SliderAndText(snap, 40, "frequency", .2, 8)

	-- Update the snapshot.
	Runtime:addEventListener("enterFrame", function(event)
		if group == CurrentGroup then
			blue.y = BlueY + math.sin(event.time / 1050) * 25

			snap:invalidate()
		end
	end)
end)

-- Effect 3 --
local NoDiscard = utils.LoadKernel("filter.custom.heat_no_discard", function(group, name)
	local image = display.newImageRect(group, "Image1.jpg", 256, 256)

	image.x, image.y = cx, cy
	image.fill.effect = name

	-- Add some controls.
	utils.SliderAndText(image, 10, "extend", .25, 250)
	utils.SliderAndText(image, 40, "frequency", .2, 8)
end)

-- Effect selection.
utils.TabBar{
	{
		name = "Normal",
		func = function()
			if CurrentGroup then -- handle first time
				CurrentGroup.isVisible = false
			end

			CurrentGroup, Normal.isVisible = Normal, true
		end
	},
	{
		name = "Snapshot",
		func = function()
			CurrentGroup.isVisible = false
			CurrentGroup, Snapshot.isVisible = Snapshot, true
		end
	},
	{
		name = "No Discard",
		func = function()
			CurrentGroup.isVisible = false
			CurrentGroup, NoDiscard.isVisible = NoDiscard, true
		end
	}
}

utils.lua

--- Just some helper utilities for Corona shaders.

--
-- Permission is hereby granted, free of charge, to any person obtaining
-- a copy of this software and associated documentation files (the
-- "Software"), to deal in the Software without restriction, including
-- without limitation the rights to use, copy, modify, merge, publish,
-- distribute, sublicense, and/or sell copies of the Software, and to
-- permit persons to whom the Software is furnished to do so, subject to
-- the following conditions:
--
-- The above copyright notice and this permission notice shall be
-- included in all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-- EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-- MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-- IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-- CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-- TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-- SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--
-- [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
--

-- Corona modules --
local widget = require("widget")

-- Exports --
local M = {}

--- Helper to load kernels
function M.LoadKernel (effect_name, func)
	local resolved = "kernel_" .. effect_name:gsub("%.", "_")

	if not package.loaded[resolved] then
		local kernel = require(resolved)

		graphics.defineEffect(kernel)
	end

	local group = display.newGroup()

	func(group, effect_name)

	group.isVisible = false

	return group
end

--
local function GetProp (effect, prefix, prop)
	if prefix then
		return effect[prefix][prop]
	else
		return effect[prop]
	end
end

--
local function SetProp (effect, prefix, prop, v)
	if prefix then
		effect[prefix][prop] = v
	else
		effect[prop] = v
	end
end

-- Make a slider with some text to its right
function M.SliderAndText (target, top, prop, min_value, max_value)
	local group, dot, prefix = target.parent, prop:find("%.")

	if dot then
		prefix, prop = prop:sub(1, dot - 1), prop:sub(dot + 1)
	end

	local range = max_value - min_value -- see the shader file for these values
	local slider = widget.newSlider{
		top = top, left = 10,
		orientation = "horizontal",
		value = 100 * (GetProp(target.fill.effect, prefix, prop) - min_value) / range,
		listener = function(event)
			SetProp(target.fill.effect, prefix, prop, min_value + (event.value / 100) * range)
		end
	}

	group:insert(slider)

	local text = display.newText(group, prop, 0, slider.y, native.systemFont, 20)

	text.anchorX, text.x = 0, slider.contentBounds.xMax + 10
end

--- Make a very basic tab bar
function M.TabBar (funcs)
	local buttons = {}

	for i, func in ipairs(funcs) do
		buttons[#buttons + 1] = { 
			label = func.name,
			selected = i == 1,
			onPress = func.func
		}
	end

	local tb = widget.newTabBar{
		top = display.contentHeight - 26,
		width = display.contentWidth,
		buttons = buttons
	}

	funcs[1].func()

	return tb
end

-- Install some theme.
widget.setTheme("widget_theme_ios")

-- Export the module.
return M