AbstractRenderer class
#include <Magnum/Text/Renderer.h>
OpenGL text renderer.
Lays out the text into mesh using given font. Use of ligatures, kerning etc. depends on features supported by particular font and its layouter.
Usage
Immutable text (e.g. menu items, credits) can be simply rendered using static methods, returning result either as data arrays or as fully configured mesh. The text can be then drawn as usual by configuring the shader and drawing the mesh:
/* Font instance, received from a plugin manager */ Containers::Pointer<Text::AbstractFont> font = …; /* Open a 12 pt font */ font->openFile("font.ttf", 12.0f); /* Populate a glyph cache */ Text::GlyphCacheGL cache{PixelFormat::R8Unorm, Vector2i{128}}; font->fillGlyphCache(cache, "abcdefghijklmnopqrstuvwxyz" "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "0123456789?!:;,. "); Shaders::VectorGL2D shader; GL::Buffer vertexBuffer, indexBuffer; GL::Mesh mesh; /* Render a 12 pt text, centered */ std::tie(mesh, std::ignore) = Text::Renderer2D::render(*font, cache, 12.0f, "Hello World!", vertexBuffer, indexBuffer, GL::BufferUsage::StaticDraw, Text::Alignment::LineCenter); /* Projection matrix is matching application window size to have the size match 12 pt in other applications, assuming a 96 DPI display and no UI scaling. */ Matrix3 projectionMatrix = Matrix3::projection(Vector2{windowSize()}); /* Draw the text on the screen */ shader .setTransformationProjectionMatrix(projectionMatrix) .setColor(0xffffff_rgbf) .bindVectorTexture(cache.texture()) .draw(mesh);
See render(AbstractFont&, const AbstractGlyphCache&, Float, const std::
While this method is sufficient for one-shot rendering of static texts, for mutable texts (e.g. FPS counters, chat messages) there is another approach that doesn't recreate everything on each text change:
/* Initialize the renderer and reserve memory for enough glyphs */ Text::Renderer2D renderer{*font, cache, 12.0f, Text::Alignment::LineCenter}; renderer.reserve(32, GL::BufferUsage::DynamicDraw, GL::BufferUsage::StaticDraw); /* Update the text occasionally */ renderer.render("Hello World Countdown: 10"); /* Draw the text on the screen */ shader.setTransformationProjectionMatrix(projectionMatrix) .setColor(0xffffff_rgbf) .bindVectorTexture(cache.texture()) .draw(renderer.mesh());
Public static functions
-
static auto render(AbstractFont& font,
const AbstractGlyphCache& cache,
Float size,
const std::
string& text, Alignment alignment = Alignment:: LineLeft) -> std:: tuple<std:: vector<Vector2>, std:: vector<Vector2>, std:: vector<UnsignedInt>, Range2D> - Render text.
-
static auto render(AbstractFont& font,
const AbstractGlyphCache& cache,
Float size,
const std::
string& text, GL:: Buffer& vertexBuffer, GL:: Buffer& indexBuffer, GL:: BufferUsage usage, Alignment alignment = Alignment:: LineLeft) -> std:: tuple<GL:: Mesh, Range2D> - Render text.
Constructors, destructors, conversion operators
-
AbstractRenderer(AbstractFont& font,
const AbstractGlyphCache& cache,
Float size,
Alignment alignment = Alignment::
LineLeft) explicit - Constructor.
-
AbstractRenderer(AbstractFont&,
AbstractGlyphCache&&,
Float,
Alignment alignment = Alignment::
LineLeft) deleted explicit - AbstractRenderer(AbstractRenderer&) deleted
- Copying is not allowed.
- AbstractRenderer(AbstractRenderer&&) noexcept
- Move constructor.
Public functions
- auto operator=(AbstractRenderer&) -> AbstractRenderer& deleted
- Copying is not allowed.
- auto operator=(AbstractRenderer&&) -> AbstractRenderer& deleted
- Move assignment is not allowed.
- auto capacity() const -> UnsignedInt
- Capacity for rendered glyphs.
- auto fontSize() const -> Float new in Git master
- Font size in points.
- auto rectangle() const -> Range2D
- Rectangle spanning the rendered text.
-
auto vertexBuffer() -> GL::
Buffer& - Vertex buffer.
-
auto indexBuffer() -> GL::
Buffer& - Index buffer.
-
auto mesh() -> GL::
Mesh& - Mesh.
-
void reserve(UnsignedInt glyphCount,
GL::
BufferUsage vertexBufferUsage, GL:: BufferUsage indexBufferUsage) - Reserve capacity for rendered glyphs.
-
void render(const std::
string& text) - Render text.
Function documentation
static std::
Render text.
| Parameters | |
|---|---|
| font | Font |
| cache | Glyph cache |
| size | Font size in points |
| text | Text to render |
| alignment | Text alignment |
Returns a tuple with vertex positions, texture coordinates, indices and rectangle spanning the rendered text. Expects that font is present in cache and that cache isn't an array.
static std::
Render text.
| Parameters | |
|---|---|
| font | Font |
| cache | Glyph cache |
| size | Font size |
| text | Text to render |
| vertexBuffer | Buffer where to store vertices |
| indexBuffer | Buffer where to store indices |
| usage | Ignored, provided just for backward compatibility |
| alignment | Text alignment |
Returns a mesh prepared for use with Shaders::font is present in cache and that cache isn't an array.
Magnum::
Constructor.
| Parameters | |
|---|---|
| font | Font |
| cache | Glyph cache |
| size | Font size |
| alignment | Text alignment |
Expects that font is present in cache and that cache isn't an array.
Magnum::
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Magnum::
Move constructor.
Performs a destructive move, i.e. the original object isn't usable afterwards anymore.
UnsignedInt Magnum::
Capacity for rendered glyphs.
void Magnum::
Reserve capacity for rendered glyphs.
Reallocates memory in buffers to hold glyphCount glyphs and prefills index buffer. The vertexBufferUsage and indexBufferUsage parameters are ignored and provided just for backward compatibility.
Initially zero capacity is reserved.
void Magnum::
Render text.
Renders the text to vertex buffer, reusing index buffer already filled with reserve(). Rectangle spanning the rendered text is available through rectangle().
Initially no text is rendered.