Sokol

Sokol (Сокол): Russian for Falcon, a smaller and more nimble bird of prey than the Eagle (Орёл, Oryol)

Minimalistic header-only cross-platform libs in C:

sokol_gfx.h: 3D-API wrapper (GL + Metal + D3D11)
sokol_app.h: app framework wrapper (entry + window + 3D-context + input)
sokol_time.h: time measurement
sokol_audio.h: minimal buffer-streaming audio playback
sokol_args.h: unified cmdline/URL arg parser for web and native apps

These are (mainly) the internal parts of the Oryol C++ framework rewritten in pure C as standalone header-only libs.

WebAssembly is a 'first-class citizen', one important motivation for the Sokol headers is to provide a collection of cross-platform APIs with a minimal footprint on the web platform while still being useful.

All headers are standalone and can be used indepedendently from each other.

Sample code is in a separate repo: https://github.com/floooh/sokol-samples

asm.js/wasm live demos: https://floooh.github.io/sokol-html5/index.html

Tiny 8-bit emulators: https://floooh.github.io/tiny8bit/

Nim bindings: https://github.com/floooh/sokol-nim

Nim samples: https://github.com/floooh/sokol-nim-samples

Why C:

easier integration with other languages
easier integration into other projects
allows even smaller program binaries than Oryol

Sokol will be a bit less convenient to use than Oryol, but that's ok since the Sokol headers are intended to be low-level building blocks.

Eventually Oryol will just be a thin C++ layer over Sokol.

A blog post with more background info: A Tour of sokol_gfx.h

sokol_gfx.h:

simple, modern wrapper around GLES2/WebGL, GLES3/WebGL2, GL3.3, D3D11 and Metal
buffers, images, shaders, pipeline-state-objects and render-passes
does not handle window creation or 3D API context initialization
does not provide shader dialect cross-translation

A triangle in C99 with GLFW and FlextGL:

#define GLFW_INCLUDE_NONE
#include "GLFW/glfw3.h"
#include "flextgl/flextGL.h"
#define SOKOL_IMPL
#define SOKOL_GLCORE33
#include "sokol_gfx.h"

int main() {

    /* create window and GL context via GLFW */
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    GLFWwindow* w = glfwCreateWindow(640, 480, "Sokol Triangle GLFW", 0, 0);
    glfwMakeContextCurrent(w);
    glfwSwapInterval(1);
    flextInit();

    /* setup sokol_gfx */
    sg_setup(&(sg_desc){0});

    /* a vertex buffer */
    const float vertices[] = {
        // positions            // colors
         0.0f,  0.5f, 0.5f,     1.0f, 0.0f, 0.0f, 1.0f,
         0.5f, -0.5f, 0.5f,     0.0f, 1.0f, 0.0f, 1.0f,
        -0.5f, -0.5f, 0.5f,     0.0f, 0.0f, 1.0f, 1.0f
    };
    sg_buffer vbuf = sg_make_buffer(&(sg_buffer_desc){
        .size = sizeof(vertices),
        .content = vertices,
    });

    /* a shader */
    sg_shader shd = sg_make_shader(&(sg_shader_desc){
        .vs.source =
            "#version 330\n"
            "in vec4 position;\n"
            "in vec4 color0;\n"
            "out vec4 color;\n"
            "void main() {\n"
            "  gl_Position = position;\n"
            "  color = color0;\n"
            "}\n",
        .fs.source =
            "#version 330\n"
            "in vec4 color;\n"
            "out vec4 frag_color;\n"
            "void main() {\n"
            "  frag_color = color;\n"
            "}\n"
    });

    /* a pipeline state object (default render states are fine for triangle) */
    sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
        .shader = shd,
        .layout = {
            .attrs = {
                [0] = { .name="position", .format=SG_VERTEXFORMAT_FLOAT3 },
                [1] = { .name="color0", .format=SG_VERTEXFORMAT_FLOAT4 }
            }
        }
    });

    /* a draw state with all the resource binding */
    sg_draw_state draw_state = {
        .pipeline = pip,
        .vertex_buffers[0] = vbuf
    };

    /* default pass action (clear to grey) */
    sg_pass_action pass_action = {0};

    /* draw loop */
    while (!glfwWindowShouldClose(w)) {
        int cur_width, cur_height;
        glfwGetFramebufferSize(w, &cur_width, &cur_height);
        sg_begin_default_pass(&pass_action, cur_width, cur_height);
        sg_apply_draw_state(&draw_state);
        sg_draw(0, 3, 1);
        sg_end_pass();
        sg_commit();
        glfwSwapBuffers(w);
        glfwPollEvents();
    }

    /* cleanup */
    sg_shutdown();
    glfwTerminate();
    return 0;
}

sokol_app.h

A minimal cross-platform application-wrapper library:

unified application entry
single window or canvas for 3D rendering
3D context initialization
event-based keyboard, mouse and touch input
supported platforms: Win32, MacOS, Linux (X11), iOS, WASM/asm.js (planned: Android, RaspberryPi)
supported 3D-APIs: GL3.3 (GLX/WGL), Metal, D3D11, GLES2/WebGL, GLES3/WebGL2

A simple clear-loop sample using sokol_app.h and sokol_gfx.h (does not include separate sokol.c/.m implementation file which is necessary to split the Objective-C code from the C code of the sample):

#include "sokol_gfx.h"
#include "sokol_app.h"

sg_pass_action pass_action;

void init(void) {
    sg_setup(&(sg_desc){
        .mtl_device = sapp_metal_get_device(),
        .mtl_renderpass_descriptor_cb = sapp_metal_get_renderpass_descriptor,
        .mtl_drawable_cb = sapp_metal_get_drawable,
        .d3d11_device = sapp_d3d11_get_device(),
        .d3d11_device_context = sapp_d3d11_get_device_context(),
        .d3d11_render_target_view_cb = sapp_d3d11_get_render_target_view,
        .d3d11_depth_stencil_view_cb = sapp_d3d11_get_depth_stencil_view
    });
    pass_action = (sg_pass_action) {
        .colors[0] = { .action=SG_ACTION_CLEAR, .val={1.0f, 0.0f, 0.0f, 1.0f} }
    };
}

void frame(void) {
    float g = pass_action.colors[0].val[1] + 0.01f;
    pass_action.colors[0].val[1] = (g > 1.0f) ? 0.0f : g;
    sg_begin_default_pass(&pass_action, sapp_width(), sapp_height());
    sg_end_pass();
    sg_commit();
}

void cleanup(void) {
    sg_shutdown();
}

sapp_desc sokol_main(int argc, char* argv[]) {
    return (sapp_desc){
        .init_cb = init,
        .frame_cb = frame,
        .cleanup_cb = cleanup,
        .width = 400,
        .height = 300,
        .window_title = "Clear (sokol app)",
    };
}

sokol_audio.h

A minimal audio-streaming API:

you provide a mono- or stereo-stream of 32-bit float samples which sokol_audio.h forwards into platform-specific backends
two ways to provide the data:
1. directly fill backend audio buffer from your callback function running in the audio thread
2. alternatively push small packets of audio data from your main loop, or a separate thread created by you
platform backends:
- Windows: WASAPI
- macOS/iOS: CoreAudio
- Linux: ALSA
- emscripten: WebAudio + ScriptProcessorNode (doesn't use the emscripten-provided OpenAL or SDL Audio wrappers)

A simple mono square-wave generator using the callback model:

// the sample callback, running in audio thread
static void stream_cb(float* buffer, int num_frames, int num_channels) {
    assert(1 == num_channels);
    static uint32_t count = 0;
    for (int i = 0; i < num_frames; i++) {
        buffer[i] = (count++ & (1<<3)) ? 0.5f : -0.5f;
    }
}

int main() {
    // init sokol-audio with default params
    saudio_setup(&(saudio_desc){
        .stream_cb = stream_cb
    });

    // run main loop
    ...

    // shutdown sokol-audio
    saudio_shutdown();
    return 0;

The same code using the push-model

#define BUF_SIZE (32)
int main() {
    // init sokol-audio with default params, no callback
    saudio_setup(&(saudio_desc){0});
    assert(saudio_channels() == 1);

    // a small intermediate buffer so we don't need to push
    // individual samples, which would be quite inefficient
    float buf[BUF_SIZE];
    int buf_pos = 0;
    uint32_t count = 0;

    // push samples from main loop
    bool done = false;
    while (!done) {
        // generate and push audio samples...
        int num_frames = saudio_expect();
        for (int i = 0; i < num_frames; i++) {
            // simple square wave generator
            buf[buf_pos++] = (count++ & (1<<3)) ? 0.5f : -0.5f;
            if (buf_pos == BUF_SIZE) {
                buf_pos = 0;
                saudio_push(buf, BUF_SIZE);
            }
        }
        // handle other per-frame stuff...
        ...
    }

    // shutdown sokol-audio
    saudio_shutdown();
    return 0;
}

sokol_time.h:

Simple cross-platform time measurement:

#include "sokol_time.h"
...
/* initialize sokol_time */
stm_setup();

/* take start timestamp */
uint64_t start = stm_now();

...some code to measure...

/* compute elapsed time */
uint64_t elapsed = stm_since(start);

/* convert to time units */
double seconds = stm_sec(elapsed);
double milliseconds = stm_ms(elapsed);
double microseconds = stm_us(elapsed);
double nanoseconds = stm_ns(elapsed);

/* difference between 2 time stamps */
uint64_t start = stm_now();
...
uint64_t end = stm_now();
uint64_t elapsed = stm_diff(end, start);

/* compute a 'lap time' (e.g. for fps) */
uint64_t last_time = 0;
while (!done) {
    ...render something...
    double frame_time_ms = stm_ms(stm_laptime(&last_time));
}

sokol_args.h

Unified argument parsing for web and native apps. Uses argc/argv on native platforms and the URL query string on the web.

Example URL with one arg:

https://floooh.github.io/tiny8bit/kc85.html?type=kc85_4

The same as command line app:

kc85 type=kc85_4

Parsed like this:

#include "sokol_args.h"

int main(int argc, char* argv[]) {
    sargs_setup(&(sargs_desc){ .argc=argc, .argv=argv });
    if (sargs_exists("type")) {
        if (sargs_equals("type", "kc85_4")) {
            // start as KC85/4
        }
        else if (sargs_equals("type", "kc85_3")) {
            // start as KC85/3
        }
        else {
            // start as KC85/2
        }
    }
    sargs_shutdown();
    return 0;
}

See the sokol_args.h header for a more complete documentation, and the Tiny Emulators for more interesting usage examples.

Overview of planned features

A list of things I'd like to do next:

sokol_gfx.h planned features:

use a per-pool-slot generation counter as 'unique tag' in the resource handles, and let the application decide whether slots should be disabled when their generation counter overflows, or whether the generation counter should simply wrap around
separate setting the pipeline from binding buffer and image resources:
- mark sg_apply_draw_state() and sg_draw_state as "deprecated"
- new function sg_apply_pipeline(sg_pipeline pip) to set the current pipeline object, must be called inside a pass
- new struct sg_bindings, same as sg_draw_state, but without the pipeline (only buffers and images for the two shader stages)
- new function sg_apply_bindings(const sg_bindings* bindings) to update the resource bindings of the currently active pipeline
- WHY: this fixes an awkward function call sequence when just updating a buffer- or image-binding via sg_apply_draw_state(), currently the uniform blocks must also be updated, since the sg_apply_draw_state() might have changed the currently set pipeline (but this isn't necessary if the pipeline hasn't changed):
```
    sg_apply_draw_state(&draw_state);
    sg_apply_uniform_block(...);
    sg_draw(...);
    /* just change a buffer binding... */
    draw_state.vertex_buffers[0] = buf;
    sg_apply_uniform_block(...);
    /* need to also update uniform blocks 
       now even though pipeline hasn't changed
    */
    sg_apply_uniform_block(...);
    sg_draw(...);
```
  With the new API this would look like this:
```
      sg_apply_pipeline(pip);
      sg_apply_bindings(&bindings);
      sg_apply_uniform_block(...);
      sg_draw(...);
      /* changing a buffer binding doesn't require other calls */
      bindings.vertex_buffers[0] = buf;
      sg_apply_bindings(&bindings);
      sg_draw(...);
```
(hmm, looking at the code above it probably also makes sense to add a sg_apply_uniforms(...) as an alias for sg_apply_uniform_block)

sokol_app.h planned features:

Mainly some "missing features" for desktop apps:

allow 'programmatic quit' requested by the application
allow to intercept the window close button, so that the app can show a 'do you really want to quit?' dialog box
define an application icon
change the window title on existing window
allow to programmatically activate and deactivate fullscreen
pointer lock
show/hide mouse cursor
allow to change mouse cursor image (at first only switch between system-provided standard images)

Big stuff:

Android support (currently WIP)

sokol_audio.h planned features:

implement an alternative WebAudio backend using Audio Worklets and WASM threads

Potential new sokol headers:

system clipboard support
query filesystem standard locations
simple file access API (at least async file/URL loading)
gamepad support
simple cross-platform touch gesture recognition

Updates

29-Oct-2018:
- sokol_gfx.h has a new function sg_append_buffer() which allows to append new data to a buffer multiple times per frame and interleave this with draw calls. This basically implements the D3D11_MAP_WRITE_NO_OVERWRITE update strategy for buffer objects. For example usage, see the updated Dear ImGui samples in the sokol_samples repo
- the GL state cache in sokol_gfx.h handles buffers bindings in a more robust way, previously it might have happened that the buffer binding gets confused when creating buffers or updating buffer contents in the render loop
17-Oct-2018: sokol_args.h added
26-Sep-2018: sokol_audio.h ready for prime time :)
11-May-2018: sokol_gfx.h now autodetects iOS vs MacOS in the Metal backend during compilation using the standard define TARGET_OS_IPHONE defined in the TargetConditionals.h system header, please replace the old backend-selection defines SOKOL_METAL_MACOS and SOKOL_METAL_IOS with SOKOL_METAL
20-Apr-2018: 3 new context-switching functions have been added to make it possible to use sokol together with applications that use multiple GL contexts. On D3D11 and Metal, the functions are currently empty. See the new section WORKING WITH CONTEXTS in the sokol_gfx.h header documentation, and the new sample multiwindow-glfw
31-Jan-2018: The vertex layout declaration in sg_pipeline_desc had some fairly subtle flaws and has been changed to work like Metal or Vulkan. The gist is that the vertex-buffer-layout properties (vertex stride, vertex-step-rate and -step-function for instancing) is now defined in a separate array from the vertex attributes. This removes some brittle backend code which tries to guess the right vertex attribute slot if no attribute names are given, and which was wrong for shader-code-generation pipelines which reorder the vertex attributes (I stumbled over this when porting the Oryol Gfx module over to sokol-gfx). Some code samples:

// a complete vertex layout declaration with a single input buffer
// with two vertex attributes
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .buffers = {
            [0] = {
                .stride = 20,
                .step_func = SG_VERTEXSTEP_PER_VERTEX,
                .step_rate = 1
            }
        },
        .attrs = {
            [0] = {
                .name = "pos",
                .offset = 0,
                .format = SG_VERTEXFORMAT_FLOAT3,
                .buffer_index = 0
            },
            [1] = {
                .name = "uv",
                .offset = 12,
                .format = SG_VERTEXFORMAT_FLOAT2,
                .buffer_index = 0
            }
        }
    },
    ...
});

// if the vertex layout has no gaps, we can get rid of the strides and offsets:
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .buffers = {
            [0] = {
                .step_func = SG_VERTEXSTEP_PER_VERTEX,
                .step_rate=1
            }
        },
        .attrs = {
            [0] = {
                .name = "pos",
                .format = SG_VERTEXFORMAT_FLOAT3,
                .buffer_index = 0
            },
            [1] = {
                .name = "uv",
                .format = SG_VERTEXFORMAT_FLOAT2,
                .buffer_index = 0
            }
        }
    },
    ...
});

// we can also get rid of the other default-values, which leaves buffers[0]
// as all-defaults, so it can disappear completely:
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .attrs = {
            [0] = { .name = "pos", .format = SG_VERTEXFORMAT_FLOAT3 },
            [1] = { .name = "uv", .format = SG_VERTEXFORMAT_FLOAT2 }
        }
    },
    ...
});

// and finally on GL3.3 and Metal and we don't need the attribute names
// (on D3D11, a semantic name and index must be provided though)
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .attrs = {
            [0] = { .format = SG_VERTEXFORMAT_FLOAT3 },
            [1] = { .format = SG_VERTEXFORMAT_FLOAT2 }
        }
    },
    ...
});

Please check the sample code in https://github.com/floooh/sokol-samples for more examples!

Enjoy!

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

README.md

README.md

Sokol

Why C:

sokol_gfx.h:

sokol_app.h

sokol_audio.h

sokol_time.h:

sokol_args.h

Overview of planned features

sokol_gfx.h planned features:

sokol_app.h planned features:

sokol_audio.h planned features:

Potential new sokol headers:

Updates

Files

README.md

Latest commit

History

README.md

File metadata and controls

Sokol

Why C:

sokol_gfx.h:

sokol_app.h

sokol_audio.h

sokol_time.h:

sokol_args.h

Overview of planned features

sokol_gfx.h planned features:

sokol_app.h planned features:

sokol_audio.h planned features:

Potential new sokol headers:

Updates