-- $Id: ShieldJitter.lua 3171 2008-11-06 09:06:29Z det $
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local ShieldJitter = {}
ShieldJitter.__index = ShieldJitter

local warpShader
local timerUniform,strengthUniform
local sphereList

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function ShieldJitter.GetInfo()
  return {
    name      = "ShieldJitter",
    backup    = "", --// backup class, if this class doesn't work (old cards,ati's,etc.)
    desc      = "",

    layer     = 16, --// extreme simply z-ordering :x

    --// gfx requirement
    fbo       = true,
    shader    = true,
    distortion= true,
    rtt       = false,
    ctt       = true,
    intel     = 0,
  }
end

ShieldJitter.Default = {
  layer = 16,

  pos        = {0,0,0}, --// start pos
  life       = math.huge,

  size       = 600,
  --precision  = 26, --// bias the used polies for a sphere

  strength   = 0.015,
  texture    = 'bitmaps/GPL/Lups/grass5.png',
  --texture    = 'bitmaps/GPL/Lups/perlin_noise.jpg',

  repeatEffect = false,
  dieGameFrame = math.huge
}

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function ShieldJitter:BeginDrawDistortion()
  gl.UseShader(warpShader)
  gl.Uniform(timerUniform,  Spring.GetGameSeconds()*0.1)

  gl.Culling(GL.FRONT) --FIXME: check if camera is in the sphere
end

function ShieldJitter:EndDrawDistortion()
  gl.UseShader(0)
  gl.Texture(0,false)

  gl.Culling(false)
end

function ShieldJitter:DrawDistortion()
  local pos  = self.pos
  local size = self.size
  gl.Uniform(strengthUniform,  self.strength )

  gl.Texture(0,self.texture)
  gl.PushMatrix()
  gl.Translate(pos[1],pos[2],pos[3])
  gl.Scale(size,size,size)
  gl.CallList(sphereList)
  gl.PopMatrix()
end

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function ShieldJitter.Initialize()
  warpShader = gl.CreateShader({
    vertex = [[
      uniform float timer;
      uniform float strength;

      varying float scale;
      varying vec2 texCoord;

	void main()
	{
          gl_Position    = ftransform();
          texCoord       = gl_MultiTexCoord0.st + timer;

          vec3 normal  = normalize(gl_NormalMatrix * gl_Normal);
          vec3 nvertex = normalize(vec3(gl_ModelViewMatrix * gl_Vertex));
          scale = strength*abs(dot( normal,nvertex ));
	}
    ]],
    fragment = [[
      uniform sampler2D noiseMap;

      varying float scale;
      varying vec2 texCoord;

      void main(void)
      {
          vec2 noiseVec;
          noiseVec = texture2D(noiseMap, texCoord).yz - 0.5;
          noiseVec *= scale;

          gl_FragColor = vec4(noiseVec,0.0,gl_FragCoord.z);
      }

    ]],
    uniformInt = {
      noiseMap = 0,
    },
    uniformFloat = {
      timer = 0,
      strength = 0.015,
    }
  })

  if (warpShader == nil) then
    print(PRIO_MAJOR,"LUPS->ShieldJitter: shader error: "..gl.GetShaderLog())
    return false
  end

  timerUniform    = gl.GetUniformLocation(warpShader, 'timer')
  strengthUniform = gl.GetUniformLocation(warpShader, 'strength')

  sphereList = gl.CreateList(DrawSphere,0,0,0,1,22)
end

function ShieldJitter.Finalize()
  gl.DeleteShader(warpShader)
  gl.DeleteList(sphereList)
  gl.DeleteTexture(tex)
end

function ShieldJitter.ViewResize(viewSizeX, viewSizeY)
end

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function ShieldJitter:Update()
end

-- used if repeatEffect=true;
function ShieldJitter:ReInitialize()
  self.dieGameFrame = self.dieGameFrame + self.life
end

function ShieldJitter:CreateParticle()
end

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function ShieldJitter.Create(Options)
  local newObject = MergeTable(Options, ShieldJitter.Default)
  setmetatable(newObject,ShieldJitter)  -- make handle lookup
  newObject:CreateParticle()
  return newObject
end

function ShieldJitter:Destroy()
  gl.DeleteTexture(self.texture)
end

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return ShieldJitter