Struct GlBackendBuilder 

pub struct GlBackendBuilder { /* private fields */ }

Builder for the GL backend.

Examples

use retroglyph_core::color::Style;
use retroglyph_gl::GlBackendBuilder;
use retroglyph_window::winit::{WindowConfig, run_windowed};

let renderer = GlBackendBuilder::new()
    .grid_size(80, 25)
    .scale(2)
    .build()
    .expect("gl backend init failed");
let config = WindowConfig::fit(&renderer, "My Game", None, true);
run_windowed(config, renderer, move |term| {
    term.draw(|s| s.print((0, 0), "Hello from retroglyph-gl!", Style::default()))
        .ok();
})
.expect("event loop failed");

Implementations

impl GlBackendBuilder

pub const fn new() -> Self

A new builder with an 80x25 grid at scale 1 and no font yet (the default-font feature supplies one at build time if none is set).

pub const fn grid_size(self, cols: u16, rows: u16) -> Self

Sets the grid size in cells.

pub const fn scale(self, scale: u16) -> Self

Sets the integer pixel scale (each glyph pixel becomes scalexscale physical pixels).

pub fn font(self, fonts: impl Into<FontChain<'static>>) -> Self

Sets the fonts glyphs are resolved through, overriding the default-font embedded font.

Takes either a single BitmapFont or a whole FontChain, since a lone font is a chain of one. A chain is how a grid draws characters CP437 has no mapping for (quadrants, sextants, braille): the extra coverage comes from a fallback font built with BitmapFont::with_charset, every font in the chain is packed into the same glyph atlas, and the glyph is drawn from that atlas, so it takes the cell’s foreground color like any other glyph (unlike a tileset sprite, which carries its own colors).

Every font in a chain must agree on its glyph size, since that is the grid’s cell size, and the chain’s glyphs must fit the atlas’s 16-bit slot space; otherwise build fails.

Examples

use retroglyph_gl::GlBackendBuilder;
use retroglyph_window::font::{BitmapFont, FontChain, unscii16};

// A fallback font declaring the quadrant glyphs CP437 has no mapping for.
static QUADRANTS: [u8; 3 * 16] = [0; 3 * 16];
const CHARSET: [(char, u8); 3] = [('▘', 0), ('▝', 1), ('▖', 2)];
static FALLBACKS: [BitmapFont; 1] =
    [BitmapFont::with_charset(&QUADRANTS, 8, 16, 3, &CHARSET)];

let renderer = GlBackendBuilder::new()
    .font(FontChain::new(unscii16::FONT, &FALLBACKS))
    .build()
    .expect("gl backend init failed");

pub fn tileset(self, opts: TilesetOptions) -> Self

Registers a PNG sprite tileset (issue #366). Glyphs a tileset maps override the bitmap font for those codepoints; register multiple and later ones win on codepoint collision. Build the options with TilesetOptions::builder.

Available only with the tilesets feature.

pub fn build(self) -> Result<GlRenderer, GlBackendError>

Builds the GlRenderer.

The renderer holds no GL context yet; the context is created when the windowing loop calls Presenter::init_surface.

Errors

Returns GlBackendError::NoFont if no font was set and the default-font feature is disabled, GlBackendError::MixedGlyphSizes if the configured chain’s fonts disagree on their glyph size, GlBackendError::FontChainTooLarge if the chain’s glyphs overflow the atlas’s slot space, GlBackendError::ZeroScale if scale is 0, GlBackendError::ZeroGrid if either grid dimension is 0, or GlBackendError::SurfaceTooLarge if cols/rows/scale combine to a surface wider or taller than u32::MAX physical pixels.

Trait Implementations

impl Clone for GlBackendBuilder

fn clone(&self) -> GlBackendBuilder

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for GlBackendBuilder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for GlBackendBuilder

fn default() -> Self

Returns the “default value” for a type.