onedraw

GPU-driven sdf 2D renderer drop-in library

onedraw is designed to render everything in a single draw call, maximizing GPU efficiency for 2D graphics. More details can be found in the documentation. It relies on Apple Metal API, wave instructions, and indirect draw calls, so adapting it to other graphics APIs would require significant changes (but feel free to contact me if you want to do a port).

Screenshot

Features

• Single draw call rendering – as the name suggests, all primitives are drawn in one draw call.
• Hierarchical tile-based binning – the compute shader processes only the primitives that influence each tile, reducing wasted work.
• Shader-based alpha blending – all blending operations are handled in the shader, no framebuffer read/write required.
• Anti-aliasing – smooth edges using signed distance functions.
• Lightweight and minimal – drop-in library with minimal dependencies.
• Baked font – ready-to-use text rendering (custom fonts are planned).
• Wide shape support – box, blurred box, rectangle, oriented box/rectangle, triangle, triangle ring, disc, circle, ellipse, arc, sector, textured quad, oriented textured quad.
• Shape operations – shapes can be grouped (boolean add), smooth minimum is supported for more organic shapes and outline can be drawn around entire group.
• C99 API – although the renderer is implemented in C++ using MetalCPP, the public interface is fully C99, so it can be used in C projects. All examples are written in C.

Integration

1. Copy all files from the /lib folder.
2. Add onedraw.cpp to your build system.
3. Create your window and provide the Metal device and drawable object.
4. Link with Metal framework

Minimal example

#include <stdlib.h>
#include <stdio.h>

#define SOKOL_METAL
#include "sokol_app.h"

#include "../lib/onedraw.h"

struct onedraw* renderer;

void init(void)
{
    renderer = od_init( &(onedraw_def)
    {
        .metal_device = (void*)sapp_metal_get_device(),
        .preallocated_buffer = malloc(od_min_memory_size()),
        .viewport_width = (uint32_t) sapp_width(),
        .viewport_height = (uint32_t) sapp_height()
    });
}

void frame(void)
{
    od_begin_frame(renderer);
    od_draw_text(renderer, 0, 0, "Hello world!", 0xffffffff);
    od_end_frame(renderer, (void*)sapp_metal_get_current_drawable());
}

void cleanup(void)
{
    od_terminate(renderer);
    free(renderer);
}

sapp_desc sokol_main(int argc, char* argv[])
{
    return (sapp_desc) 
    {
        .width = 1280,
        .height = 720,
        .init_cb = init,
        .frame_cb = frame,
        .cleanup_cb = cleanup
    };
}

See tests/test.c for an example testing all features using sokol_app.h for the window management.

Build

Follow the step to build and run the test program

• mkdir build
• cd build
• cmake ..
• make
• ./test

Links and references

Metal API

Inigo Quilez's articles

Sokol libraries

Satoshi font