elm-webgl-triangles-2

module Triangles exposing (..)

import WebGL as GL exposing (..)
import Math.Vector2 exposing (Vec2, vec2)
import Math.Vector3 exposing (Vec3, vec3)
import Math.Matrix4 exposing (..)
import Html exposing (..)
import Time exposing (Time, millisecond)

type alias Model =
  { rotation : Float
  }

type alias Vertex =
    { position : Vec2
    , color : Vec3
    }

type alias Varying =
    { vColor : Vec3
    }

type Msg = Tick Time

update : Msg -> Model -> ( Model, Cmd Msg )
update e m = {m | rotation = m.rotation + 0.01} ! []

--main : Program Never {} {}
main =
    Html.program
        { init =
            Model 1.0 ! []
        , view = view
        , update = update
        , subscriptions = subscriptions
        }


subscriptions : Model -> Sub Msg
subscriptions model =
  Time.every millisecond Tick

view : Model -> Html msg
view m =
    GL.toHtml
        []
        [ boxEntity m.rotation ]


boxEntity : Float -> Entity
boxEntity f =
    GL.entity
        vertexShader
        fragmentShader
        boxMesh
        { rotation = makeRotate f (vec3 1 1 1) }


vertexShader : Shader { position : Vec2, color : Vec3 } { rotation : Mat4 } { vColor : Vec3 }
vertexShader =
    [glsl|

  precision mediump float;
  attribute vec2 position;
  attribute vec3 color;
  uniform mat4 rotation;
  varying vec3 vColor;

  void main () {
    gl_Position = rotation * vec4(position, 0.0, 1.0);
    vColor = color;
  }

  |]


fragmentShader : Shader {} { rotation : Mat4 } Varying
fragmentShader =
    [glsl|

  precision mediump float;
  varying vec3 vColor;

  void main () {
    gl_FragColor = vec4(vColor, 1.);
  }

  |]


boxMesh : Mesh Vertex
boxMesh =
    GL.triangles
        [ ( (Vertex (vec2 -1 1) (vec3 1 0 0))
          , (Vertex (vec2 1 1) (vec3 0 1 0))
          , (Vertex (vec2 -1 -1) (vec3 0 0 1))
          )
        , ( (Vertex (vec2 -1 -1) (vec3 1 0 0))
          , (Vertex (vec2 1 -1) (vec3 0 1 0))
          , (Vertex (vec2 1 1) (vec3 0 0 1))
          )
        ]