A rendering engine library for Go supporting both SDL2 and WebAssembly (HTML Canvas) targets.
選択できるのは25トピックまでです。 トピックは、先頭が英数字で、英数字とダッシュ('-')を使用した35文字以内のものにしてください。
Noah Petherbridge b4a1979a8b Bugfix on space character 4ヶ月前
canvas Make it a Go module + minor tweaks 1年前
event Spacebar event 4ヶ月前
examples Change public API to use int instead of int32 everywhere 1年前
sdl Bugfix on space character 4ヶ月前
.gitignore Add WebAssembly Hello World Example 1年前
LICENSE.md Clean up repository for stand-alone release 1年前
README.md Change public API to use int instead of int32 everywhere 1年前
color.go Maximize SDL2 window 10ヶ月前
ellipse.go Better Ellipse Drawing Algorithm 1年前
functions.go Change public API to use int instead of int32 everywhere 1年前
go.mod Make it a Go module + minor tweaks 1年前
go.sum Maximize SDL2 window 10ヶ月前
image.go Make it a Go module + minor tweaks 1年前
interface.go Text.IsZero to check more values 11ヶ月前
point.go Add Point Comparator Function and Tests 1年前
point_test.go Add Point Comparator Function and Tests 1年前
rect_test.go Change public API to use int instead of int32 everywhere 1年前
shapes.go Change public API to use int instead of int32 everywhere 1年前
version.go Make it a Go module + minor tweaks 1年前


Render: Go Graphics Library


Render is a graphics rendering library for Go.

It supports SDL2 and HTML Canvas back-ends enabling its use for both desktop applications (Linux, Mac and Windows) and WebAssembly modules for running in the web browser.


Notice: github.com/kirsle/render is a mirror to the upstream repository at git.kirsle.net/go/render. Issues and pull requests will be accepted at GitHub.


package main

import (

func main() {
    mw := sdl.New("Hello World", 320, 240)

    if err := mw.Setup(); err != nil {

    // Text that we're gonna draw in the window.
    text := render.Text{
        Text:         "Hello, world!",
        Size:         24,
        Color:        render.SkyBlue,
        Shadow:       render.Blue,
        FontFilename: "DejaVuSans.ttf",

    // Compute the rendered size of the text.
    rect, _ := mw.ComputeTextRect(text)

    for {
        // Blank the window.

        // Poll for events (mouse clicks, keyboard keys, etc.)
        ev, err := mw.Poll()
        if err != nil {

        // Escape key closes the window.
        if ev.Escape {

        // Get the window size.
        w, h := mw.WindowSize()

        // Draw the text centered in the window.
        mw.DrawText(text, render.NewPoint(
            (w/2) - (rect.W/2),
            (h/2) - (rect.H/2),


See the examples/ directory for examples. More will come eventually, including some WebAssembly examples.

Project Status: Alpha

This module was written as part of my drawing-based maze game, code named Project: Doodle. It is currently in alpha status and its API may change and be cleaned up in the future.

Drawing Methods (Engine)

This package provides some basic primitive drawing methods which are implemented for SDL2 (desktops) and HTML Canvas (WebAssembly). See the render.Engine interface. The drawing methods supported are:

  • Clear(Color): blank the window and fill it with this color.
  • DrawPoint(Color, Point): draw a single pixel at a coordinate.
  • DrawLine(Color, A Point, B Point): draw a line between two points.
  • DrawRect(Color, Rect): draw a rectangle outline between two points.
  • DrawBox(Color, Rect): draw a filled rectangle between two points.
  • DrawText(Text, Point): draw text at a location.
  • StoreTexture(name string, image.Image): load a Go image.Image object into the engine as a “texture” that can be re-used and pasted on the canvas.
  • LoadTexture(filename string): load an image from disk into a texture.
  • Copy(Texturer, src Rect, dst Rect): copy a texture onto the canvas.

Drawing Types

This package defines a handful of types useful for drawing operations. See the godoc for full details.

  • Color: an RGBA color holding uint8 values for each channel.
    • NewRGBA(red, green, blue, alpha uint8) to construct a new color.
  • Point: holds an X,Y pair of coordinates.
  • Rect: holds an X,Y and a W,H value.
  • Text: holds text and configuration for rendering (color, stroke, shadow, size, etc.)

Shape Generator Functions

The render package includes a few convenience functions for drawing complex shapes.

The generator functions return a channel that yields all of the Points that should be drawn to complete the shape. Example:

var (
    A Point = render.NewPoint(10, 10)
    B Point = render.NewPoint(15, 20)

for pt := range render.IterLine(A, B) {
    engine.DrawPoint(render.Red, pt)
  • IterLine(A Point, B Point): draw a line from A to B.
  • IterRect(A Point, B Point): iterate all the points to draw a rectangle.
  • IterEllipse(A Point, B Point): draw an elipse fitting inside the rectangle bounded by points A and B.