#
#   TODO: Needs Depth-Buffer first!
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#


import std/times

import ../src/semicongine

const
  TopLeftFront = newVec3f(-0.5'f32, -0.5'f32, -0.5'f32)
  TopRightFront = newVec3f(0.5'f32, -0.5'f32, -0.5'f32)
  BottomRightFront = newVec3f(0.5'f32, 0.5'f32, -0.5'f32)
  BottomLeftFront = newVec3f(-0.5'f32, 0.5'f32, -0.5'f32)
  TopLeftBack = newVec3f(0.5'f32, -0.5'f32, 0.5'f32)
  TopRightBack = newVec3f(-0.5'f32, -0.5'f32, 0.5'f32)
  BottomRightBack = newVec3f(-0.5'f32, 0.5'f32, 0.5'f32)
  BottomLeftBack = newVec3f(0.5'f32, 0.5'f32, 0.5'f32)
const
  cube_pos = @[
    TopLeftFront, TopRightFront, BottomRightFront, BottomLeftFront, # front
    TopLeftBack, TopRightBack, BottomRightBack, BottomLeftBack, # back
    TopLeftBack, TopLeftFront, BottomLeftFront, BottomLeftBack, # left
    TopRightBack, TopRightFront, BottomRightFront, BottomRightBack, # right
    TopLeftBack, TopRightBack, TopRightFront, TopLeftFront, # top
    BottomLeftFront, BottomRightFront, BottomRightBack, BottomLeftBack, # bottom
  ]
  R = newVec4f(1, 0, 0, 1)
  G = newVec4f(0, 1, 0, 1)
  B = newVec4f(0, 0, 1, 1)
  cube_color = @[
    R, R, R, R,
    R * 0.5'f32, R * 0.5'f32, R * 0.5'f32, R * 0.5'f32,
    G, G, G, G,
    G * 0.5'f32, G * 0.5'f32, G * 0.5'f32, G * 0.5'f32,
    B, B, B, B,
    B * 0.5'f32, B * 0.5'f32, B * 0.5'f32, B * 0.5'f32,
  ]
var
  tris: seq[array[3, uint16]]
for i in 0'u16 ..< 6'u16:
  let off = i * 4
  tris.add [off + 0'u16, off + 1'u16, off + 2'u16]
  tris.add [off + 2'u16, off + 3'u16, off + 0'u16]

when isMainModule:
  var myengine = initEngine("Hello cube")

  const
    inputs = @[
      attr[Vec3f]("position"),
      attr[Vec4f]("color", memoryPerformanceHint=PreferFastWrite),
    ]
    intermediate = @[attr[Vec4f]("outcolor")]
    uniforms = @[
      attr[Mat4]("projection"),
      attr[Mat4]("view"),
      attr[Mat4]("model"),
    ]
    fragOutput = @[attr[Vec4f]("color")]
    (vertexCode, fragmentCode) = compileVertexFragmentShaderSet(
      inputs=inputs,
      intermediate=intermediate,
      outputs=fragOutput,
      uniforms=uniforms,
      vertexCode="""outcolor = color; gl_Position = (Uniforms.projection * Uniforms.view * Uniforms.model) * vec4(position, 1);""",
      fragmentCode="color = outcolor;",
    )
  myengine.setRenderer(myengine.gpuDevice.simpleForwardRenderPass(vertexCode, fragmentCode))
  var cube = newScene("scene", newEntity("cube", {"mesh": Component(newMesh(positions=cube_pos, indices=tris, colors=cube_color))}))
  cube.addShaderGlobal("projection", Unit4f32)
  cube.addShaderGlobal("view", Unit4f32)
  cube.addShaderGlobal("model", Unit4f32)
  myengine.addScene(cube, inputs, @[], transformAttribute="")

  var t: float32 = cpuTime()
  while myengine.updateInputs() == Running and not myengine.keyWasPressed(Escape):
    setShaderGlobal(cube, "model", translate3d(0'f32, 0'f32, 10'f32) * rotate3d(t, Yf32))
    setShaderGlobal(cube, "projection",
      perspective(
        float32(PI / 4),
        float32(myengine.getWindow().size[0]) / float32(myengine.getWindow().size[0]),
        0.1'f32,
        100'f32
      )
    )
    t = cpuTime()

    myengine.renderScene(cube)

  myengine.destroy()