magnum/doc/shaders.dox

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namespace Magnum {
/** @page shaders Builtin shaders
@brief Overview and basic usage of builtin shaders.

@m_keywords{Shaders}

@tableofcontents
@m_footernavigation

Magnum contains a set of general-purpose shaders for easy prototyping, UI
rendering and data visualization/debugging in both 2D and 3D scenes. The
following shaders are available, see documentation of each class for sample
output and example setup:

-   @ref Shaders::Flat "Shaders::Flat*D" --- flat shading using single color or
    texture
-   @ref Shaders::Vector "Shaders::Vector*D" --- colored vector graphics
-   @ref Shaders::DistanceFieldVector "Shaders::DistanceFieldVector*D" --
    colored and outlined vector graphics
-   @ref Shaders::VertexColor "Shaders::VertexColor*D" --- vertex-colored meshes
-   @ref Shaders::Phong --- Phong shading using colors or textures, 3D only
-   @ref Shaders::MeshVisualizer --- wireframe visualization, 3D only

All the builtin shaders can be used on unextended OpenGL 2.1 and OpenGL ES 2.0
/ WebGL 1.0, but they try to use the most recent technology available to have
them as efficient as possible on every configuration.

@section shaders-usage Usage

Shader usage is divided into two parts: configuring vertex attributes in the
mesh and configuring the shader itself.

Each shader expects some set of vertex attributes, thus when adding vertex
buffer into the mesh, you need to specify which shader attributes are on which
position in the buffer. See @ref GL::Mesh::addVertexBuffer() for details and
usage examples. Example mesh configuration for @ref Shaders::Phong shader:

@snippet MagnumShaders.cpp shaders-setup

Each shader then has its own set of configuration functions. Some configuration
is static, specified commonly as flags in constructor, directly affecting
compiled shader code. Other configuration is specified through uniforms and
various binding points, commonly exposed through various setters. All shader
uniforms have a reasonable defaults so you are able to see at least something
when using the shader directly without any further configuration, but in most
cases you may want to specify at least the transformation/projection matrices.
Example configuration and rendering using @link Shaders::Phong @endlink:

@snippet MagnumShaders.cpp shaders-rendering

@section shaders-generic Generic vertex attributes and framebuffer attachments

Many shaders share the same vertex attribute definitions, such as positions,
normals, texture coordinates etc. It's thus possible to configure the mesh
for a *generic* shader and then render it with any compatible shader.
Definition of all generic attributes is available in the @ref Shaders::Generic
class. Configuration of the above mesh using generic attributes could then look
like this:

@snippet MagnumShaders.cpp shaders-generic

Note that in this particular case both configurations are equivalent, because
@ref Shaders::Phong also uses generic vertex attribute definitions. Then you
can render the mesh using @ref Shaders::Phong shader like above, or use for
example @ref Shaders::Flat3D or even @ref Shaders::MeshVisualizer with the same
mesh reconfiguration. The unused attributes will be simply ignored.

@snippet MagnumShaders.cpp shaders-meshvisualizer

The @ref MeshTools::compile() utility configures meshes using generic vertex
attribute definitions to make them usable with any shader.

Besides vertex attributes, the @ref Shaders::Generic contains generic
definitions for framebuffer outputs as well --- in many cases a shader has just
one (color) output, but some shaders such as @ref Shaders::Flat or
@ref Shaders::Phong offer an object ID output as well. A setup equivalent to
what's done in Flat shader's @ref Shaders-Flat-object-id but using the generic
definitions would look like this:

@snippet MagnumShaders.cpp shaders-generic-object-id
*/
}