Mesh forms geometry from the specified vertices. Each vertex contains a bunch of attributes, defined as a custom record type, e.g.:

type alias Attributes =
    { position : Vec3
    , color : Vec3
    }

The supported types in attributes are: Int, Float, Texture and Vec2, Vec3, Vec4, Mat4 from the linear-algebra package.

Do not generate meshes in view, read more about this here.

Triangles are the basic building blocks of a mesh. You can put them together to form any shape.

So when you create triangles you are really providing three sets of attributes that describe the corners of each triangle.

Shaders are programs for running many computations on the GPU in parallel. They are written in a language called GLSL. Read more about shaders here.

Normally you specify a shader with a [glsl| |] block. Elm compiler will parse the shader code block and derive the type signature for your shader.

• attributes define vertices in the mesh;
• uniforms allow you to pass scene parameters like transformation matrix, texture, screen size, etc.;
• varyings define the output from the vertex shader.

attributes, uniforms and varyings are records with the fields of the following types: Int, Float, Texture and Vec2, Vec3, Vec4, Mat4 from the linear-algebra package.

Conceptually, an encapsulation of the instructions to render something.

Packages a vertex shader, a fragment shader, a mesh, and uniforms as an Entity. This specifies a full rendering pipeline to be run on the GPU. You can read more about the pipeline here.

The vertex shader receives attributes and uniforms and returns varyings and gl_Position—the position of the vertex on the screen, defined as vec4(x, y, z, w), that means (x/w, y/w, z/w) in the clip space coordinates:

--   (-1,1,1) +================+ (1,1,1)
--           /|               /|
--          / |     |        / |
--(-1,1,-1)+================+ (1,1,-1)
--         |  |     | /     |  |
--         |  |     |/      |  |
--         |  |     +-------|->|
-- (-1,-1,1|) +--(0,0,0)----|--+ (1,-1,1)
--         | /              | /
--         |/               |/
--         +================+
--   (-1,-1,-1)         (1,-1,-1)

The fragment shader is called for each pixel inside the clip space with varyings and uniforms and returns gl_FragColor—the color of the pixel, defined as vec4(r, g, b, a) where each color component is a float from 0 to 1.

Shaders and a mesh are cached so that they do not get resent to the GPU. It should be relatively cheap to create new entities out of existing values.

By default, depth test is enabled for you. If you need more settings, like blending or stencil test, then use entityWith.

entity =
    entityWith [ DepthTest.default ]

Render a WebGL scene with the given html attributes, and entities.

width and height html attributes resize the drawing buffer, while the corresponding css properties scale the canvas element.

To prevent blurriness on retina screens, you may want the drawing buffer to be twice the size of the canvas element.

To remove an extra whitespace around the canvas, set display: block.

By default, alpha channel with premultiplied alpha, antialias and depth buffer are enabled. Use toHtmlWith for custom options.

toHtml =
    toHtmlWith [ alpha True, antialias, depth 1 ]

The same as entity, but allows to configure an entity with settings.

Render a WebGL scene with the given options, html attributes, and entities.

Due to browser limitations, options will be applied only once, when the canvas is created for the first time.

Provides a way to enable features and change the scene behavior in toHtmlWith.

Enable alpha channel in the drawing buffer. If the argument is True, then the page compositor will assume the drawing buffer contains colors with premultiplied alpha (r * a, g * a, b * a, a).

Enable the depth buffer, and prefill it with given value each time before the scene is rendered. The value is clamped between 0 and 1.

Enable the stencil buffer, specifying the index used to fill the stencil buffer before we render the scene. The index is masked with 2^m - 1, where m >= 8 is the number of bits in the stencil buffer. The default is 0.

Enable multisample antialiasing of the drawing buffer, if supported by the platform. Useful when you need to have smooth lines and smooth edges of triangles at a lower cost than supersampling (rendering to larger dimensions and then scaling down with CSS transform).

Set the red, green, blue and alpha channels, that will be used to fill the drawing buffer every time before drawing the scene. The values are clamped between 0 and 1. The default is all 0's.

Create triangles from vertices and indices, grouped in sets of three to define each triangle by refering the vertices. This helps to avoid duplicated vertices whenever two triangles share an edge.

-- v2 +---+ v1
--    |\  |
--    | \ |
--    |  \|
-- v3 +---+ v0

For example, if you want to define a rectangle using triangles, v0 and v2 will have to be duplicated:

rectangle =
    triangles [ ( v0, v1, v2 ), ( v2, v3, v0 ) ]

This will use two vertices less:

rectangle =
    indexedTriangles [ v0, v1, v2, v3 ] [ ( 0, 1, 2 ), ( 2, 3, 0 ) ]

Connects each pair of vertices with a line.

Connects each two subsequent vertices with a line.

Similar to lineStrip, but connects the last vertex back to the first.

Draws a single dot per vertex.

Similar to triangleStrip, but creates a fan shaped output.

Creates a strip of triangles where each additional vertex creates an additional triangle once the first three vertices have been drawn.