easy-gl › Feature

Feature

An enum class used with Device::supports(), Device::require(), and Capabilities::supports(). Defines named capabilities that may or may not be present depending on the OpenGL version or extensions available.

enum class Feature {
    VertexArrayObject,
    Shader,
    Program,
    Buffer,
    BasicRendering,
    DebugOutput,
    ComputeShader,
    GeometryShader,
    TessellationShader,
    Texture3D,
    TextureFloat,
    TextureRG,
    SamplerObject,
    Instancing,
    UniformBufferObject,
    FramebufferObject,
    Multisampling,
    DrawBuffers,
    MapBuffer,
    DirectStateAccess,
    ClipControl,
    TextureCompression,
    AnisotropicFiltering,
    OpenGlOnlyImmediateMode,
    OpenGlOnlyPolygonMode,
    OpenGlOnlyLineWidthWide
};

Using Feature for runtime branching

if (device.supports(easygl::Feature::AnisotropicFiltering)) {
    tex.set_parameter(easygl::TextureTarget::Texture2D,
                       easygl::TextureParameter::MaxAnisotropy, 16.0f);
}

if (device.supports(easygl::Feature::TessellationShader)) {
    device.set_patch_vertices(3);
    // submit tessellated draw ...
} else {
    // fallback to triangle mesh ...
}

Requiring a feature (throw on missing)

// Abort early with a clear message if FBOs are not available
device.require(easygl::Feature::FramebufferObject);
device.require(easygl::Feature::UniformBufferObject);