gfx_volumetric_clouds.lua

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--

function widget:GetInfo()
  return {
    name      = "Volumetric Clouds",
    version   = 6,
    desc      = "Fog/Dust clouds that scroll with wind along the map's surface. Requires GLSL, expensive even with.",
    author    = "Anarchid, consulted and optimized by jK",
    date      = "november 2014",
    license   = "GNU GPL, v2 or later",
    layer     = -1000,
    enabled   = true
  }
end

local enabled = true


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-- Config

local mapcfg = VFS.Include("mapinfo.lua");

if (not mapcfg)or(not mapcfg.custom)or(not mapcfg.custom.clouds) then
	error("<Volumetric Clouds>: Can't find settings in mapinfo.lua!");
end

local CloudDefs = mapcfg.custom.clouds;

local gnd_min, gnd_max = Spring.GetGroundExtremes()

local function convertAltitude(input, default)
	if (input == nil or input == "auto") then 
		return default
	elseif type(input) == "number" then
		return input
	elseif (type(input) == "string" and input:match("(%d+)%%")) then
		local percent = input:match("(%d+)%%")
		return gnd_max * (percent / 100)
	end
	return input
end

CloudDefs.height = convertAltitude(CloudDefs.height, gnd_max*0.9)
CloudDefs.bottom = convertAltitude(CloudDefs.bottom, 0)
CloudDefs.fade_alt = convertAltitude(CloudDefs.fade_alt, gnd_max*0.8)

local cloudsHeight    = CloudDefs.height
local cloudsBottom    = CloudDefs.bottom or gnd_min
local cloudsColor     = CloudDefs.color
local cloudsScale     = CloudDefs.scale
local cloudsClamp     = CloudDefs.clamp_to_map or false
local speed    		  = CloudDefs.speed
local opacity    	  = CloudDefs.opacity or 0.3
local sunPenetration  = CloudDefs.sun_penetration or (-40.0)
local fade_alt    	  = CloudDefs.fade_alt
local fr,fg,fb        = unpack(cloudsColor)
local sunDir = {0,0,0}
local sunCol = {1,0,0}

assert(type(sunPenetration) == "number")
assert(type(cloudsClamp) == "boolean")
assert(type(cloudsHeight) == "number")
assert(type(cloudsBottom) == "number")
assert(type(fr) == "number")
assert(type(fg) == "number")
assert(type(fb) == "number")
assert(type(opacity) == "number")
assert(type(fade_alt) == "number")
assert(type(cloudsScale) == "number")
assert(type(speed) == "number")


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-- Automatically generated local definitions

local GL_MODELVIEW           = GL.MODELVIEW
local GL_NEAREST             = GL.NEAREST
local GL_ONE                 = GL.ONE
local GL_ONE_MINUS_SRC_ALPHA = GL.ONE_MINUS_SRC_ALPHA
local GL_PROJECTION          = GL.PROJECTION
local GL_QUADS               = GL.QUADS
local GL_SRC_ALPHA           = GL.SRC_ALPHA
local glBeginEnd             = gl.BeginEnd
local glBlending             = gl.Blending
local glCallList             = gl.CallList
local glColor                = gl.Color
local glColorMask            = gl.ColorMask
local glCopyToTexture        = gl.CopyToTexture
local glCreateList           = gl.CreateList
local glCreateShader         = gl.CreateShader
local glCreateTexture        = gl.CreateTexture
local glDeleteShader         = gl.DeleteShader
local glDeleteTexture        = gl.DeleteTexture
local glDepthMask            = gl.DepthMask
local glDepthTest            = gl.DepthTest
local glGetMatrixData        = gl.GetMatrixData
local glGetShaderLog         = gl.GetShaderLog
local glGetUniformLocation   = gl.GetUniformLocation
local glGetViewSizes         = gl.GetViewSizes
local glLoadIdentity         = gl.LoadIdentity
local glLoadMatrix           = gl.LoadMatrix
local glMatrixMode           = gl.MatrixMode
local glMultiTexCoord        = gl.MultiTexCoord
local glPopMatrix            = gl.PopMatrix
local glPushMatrix           = gl.PushMatrix
local glResetMatrices        = gl.ResetMatrices
local glTexCoord             = gl.TexCoord
local glTexture              = gl.Texture
local glRect                 = gl.Rect
local glUniform              = gl.Uniform
local glUniformMatrix        = gl.UniformMatrix
local glUseShader            = gl.UseShader
local glVertex               = gl.Vertex
local glTranslate            = gl.Translate
local spGetCameraPosition    = Spring.GetCameraPosition
local spGetCameraVectors     = Spring.GetCameraVectors
local spGetWind              = Spring.GetWind
local time                   = Spring.GetGameSeconds
local spGetDrawFrame         = Spring.GetDrawFrame

local function spEcho(words)
	Spring.Echo('<Volumetric Clouds> '..words)
end

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--
--  Extra GL constants
--

local GL_DEPTH_BITS = 0x0D56

local GL_DEPTH_COMPONENT   = 0x1902
local GL_DEPTH_COMPONENT16 = 0x81A5
local GL_DEPTH_COMPONENT24 = 0x81A6
local GL_DEPTH_COMPONENT32 = 0x81A7
local GL_RGBA32F_ARB       = 0x8814

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if (gnd_min < 0) then gnd_min = 0 end
if (gnd_max < 0) then gnd_max = 0 end
local vsx, vsy

local depthShader
local depthTexture
local fogTexture

local uniformEyePos
local uniformViewPrjInv
local uniformOffset
local uniformSundir
local uniformSunColor
local uniformTime

local offsetX = 0;
local offsetY = 0;
local offsetZ = 0;



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function widget:ViewResize()
	vsx, vsy = gl.GetViewSizes()
	if (Spring.GetMiniMapDualScreen()=='left') then
		vsx=vsx/2;
	end
	if (Spring.GetMiniMapDualScreen()=='right') then
		vsx=vsx/2
	end

	if (depthTexture) then
		glDeleteTexture(depthTexture)
	end
	
	if (fogTexture) then
		glDeleteTexture(fogTexture)
	end

	depthTexture = glCreateTexture(vsx, vsy, {
		format = GL_DEPTH_COMPONENT24,
		min_filter = GL_NEAREST,
		mag_filter = GL_NEAREST,
	});
	
	fogTexture = glCreateTexture(vsx/3, vsy/3, {
		min_filter = GL.LINEAR,
		mag_filter = GL.LINEAR,
		wrap_s = GL.CLAMP_TO_EDGE,
		wrap_t = GL.CLAMP_TO_EDGE,
		fbo = true,
	});


	if (depthTexture == nil) then
		spEcho("Removing fog widget, bad depth texture")
		widgetHandler:RemoveWidget();
	end
end

widget:ViewResize()


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local vertSrc = [[

  void main(void)
  {
    gl_TexCoord[0] = gl_MultiTexCoord0;
    gl_Position    = gl_Vertex;
  }
]]

local fragSrc = VFS.LoadFile("LuaUI/Widgets/Shaders/fog_frag.glsl");

fragSrc = fragSrc:format(
  cloudsScale, cloudsHeight, cloudsBottom, 
  cloudsColor[1], cloudsColor[2], cloudsColor[3], 
  Game.mapSizeX, Game.mapSizeZ, 
  fade_alt, opacity, sunPenetration
);

if(cloudsClamp) then
  fragSrc = '#define CLAMP_TO_MAP\n' .. fragSrc
end

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function widget:Initialize()
	if (Spring.GetMiniMapDualScreen() == 'left') then --FIXME dualscreen
		enabled = false
	end

	if (not glCreateShader) then
		enabled = false
	end

	if enabled then
		depthShader = glCreateShader({
			vertex = vertSrc,
			fragment = fragSrc,
			uniformInt = {
				tex0 = 0,
				tex1 = 1,
			},
		});

		spEcho(glGetShaderLog())
		if (not depthShader) then
			spEcho("Bad shader, reverting to non-GLSL widget.")
			enabled = false
		else
			uniformEyePos       = glGetUniformLocation(depthShader, 'eyePos')
			uniformViewPrjInv   = glGetUniformLocation(depthShader, 'viewProjectionInv')
			uniformOffset       = glGetUniformLocation(depthShader, 'offset')
			uniformSundir       = glGetUniformLocation(depthShader, 'sundir')
			uniformSunColor     = glGetUniformLocation(depthShader, 'suncolor')
			uniformTime         = glGetUniformLocation(depthShader, 'time')
		end
	end

	if not(enabled) then
		widgetHandler:RemoveWidget();
		return
	end
end


function widget:Shutdown()
	glDeleteTexture(depthTexture)
	glDeleteTexture(fogTexture)
	if (glDeleteShader) then
		glDeleteShader(depthShader)
	end
	glDeleteTexture(":l:LuaUI/Widgets/Images/rgbnoise.png");
end


local function renderToTextureFunc()
	-- render a full screen quad
	glTexture(0, depthTexture)
	glTexture(0, false)
	glTexture(1,":l:LuaUI/Widgets/Images/rgbnoise.png");
	glTexture(1, false)

	gl.TexRect(-1, -1, 1, 1, 0, 0, 1, 1)
end

local function DrawFogNew()
	--//FIXME handle dualscreen correctly!
	-- copy the depth buffer
	glCopyToTexture(depthTexture, 0, 0, 0, 0, vsx, vsy) --FIXME scale down?

	-- setup the shader and its uniform values
	glUseShader(depthShader)

	-- set uniforms
	glUniform(uniformEyePos, spGetCameraPosition())
	glUniform(uniformOffset, offsetX, offsetY, offsetZ);
	
	glUniform(uniformSundir, sunDir[1], sunDir[2], sunDir[3]);
	glUniform(uniformSunColor, sunCol[1], sunCol[2], sunCol[3]);

	glUniform(uniformTime, Spring.GetGameSeconds() * speed);

	glUniformMatrix(uniformViewPrjInv,  "viewprojectioninverse")

	-- TODO: completely reset the texture before applying shader
	-- TODO: figure out why it disappears in some places
	-- maybe add a switch to make it high-res direct-render
	gl.RenderToTexture(fogTexture, renderToTextureFunc);

	glUseShader(0)
end


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function widget:GameFrame()
	local dx,dy,dz = spGetWind();
	offsetX = offsetX-dx*speed;
	offsetY = offsetY-0.25-dy*0.25*speed;
	offsetZ = offsetZ-dz*speed;

	sunDir = {gl.GetSun('pos')}
	sunCol = {gl.GetSun('specular')}
end

widget:GameFrame()


function widget:DrawScreenEffects()
	glBlending(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA) -- in theory not needed but sometimes evil widgets disable it w/o reenabling it
	glTexture(fogTexture);
	gl.TexRect(0,0,vsx,vsy,0,0,1,1);
	glTexture(false);
end

function widget:DrawWorld()
	glBlending(false)
	DrawFogNew()
	glBlending(true)
end

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