awtk/3rd/sokol/README.md

Sokol

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

See what's new (08-Sep-2019: clamp-to-border texture sampling in sokol_gfx.h)

Live Samples via WASM.

Minimalistic STB-style cross-platform single-file-libs written in C (or rather 'the subset of C which compiles both in C and 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_fetch.h: asynchronous data streaming from HTTP and local filesystem
• sokol_args.h: unified cmdline/URL arg parser for web and native apps

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 independently from each other.

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

Command line tools: https://github.com/floooh/sokol-tools

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

Why C:

• easier integration with other languages
• easier integration into other projects
• adds only minimal size overhead to executables

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 (BUT there's now an 'official' shader-cross-compiler solution which seamlessly integrates with sokol_gfx.h and IDEs: see here for details

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"
            "layout(location=0) in vec4 position;\n"
            "layout(location=1) 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].format=SG_VERTEXFORMAT_FLOAT3,
                [1].format=SG_VERTEXFORMAT_FLOAT4
            }
        }
    });

    /* resource bindings */
    sg_bindings binds = {
        .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_pipeline(pip);
        sg_apply_bindings(&binds);
        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, Android (planned: 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_fetch.h

Load entire files, or stream data asynchronously over HTTP (emscripten/wasm) or the local filesystem (all native platforms).

Simple C99 example loading a file into a static buffer:

#include "sokol_fetch.h"

static void response_callback(const sfetch_response*);

#define MAX_FILE_SIZE (1024*1024)
static uint8_t buffer[MAX_FILE_SIZE];

// application init
static void init(void) {
    ...
    // setup sokol-fetch with default config:
    sfetch_setup(&(sfetch_desc_t){0});

    // start loading a file into a statically allocated buffer:
    sfetch_send(&(sfetch_request_t){
        .path = "hello_world.txt",
        .callback = response_callback
        .buffer_ptr = buffer,
        .buffer_size = sizeof(buffer)
    });
}

// per frame...
static void frame(void) {
    ...
    // need to call sfetch_dowork() once per frame to 'turn the gears':
    sfetch_dowork();
    ...
}

// the response callback is where the interesting stuff happens:
static void reponse_callback(const sfetch_response_t* response) {
    if (response->fetched) {
        // data has been loaded into the provided buffer, do something
        // with the data...
        const void* data = response->buffer_ptr;
        uint64_t data_size = response->fetched_size;
    }
    // the finished flag is set both on success and failure
    if (response->failed) {
        // oops, something went wrong
        switch (response->error_code) {
            SFETCH_ERROR_FILE_NOT_FOUND: ...
            SFETCH_ERROR_BUFFER_TOO_SMALL: ...
            ...
        }
    }
}

// application shutdown
static void shutdown(void) {
    ...
    sfetch_shutdown();
    ...
}

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:

• 2 small additions to the per-pool-slot generation counters in sokol_gfx.h:
  • an sg_setup() option to disable a pool slot when it's generation counter overflows, this makes the dangling-check for resource ids watertight at the cost that the pool will run out of slots at some point
  • instead of the 16/16-bit split in the resource ids for unique-tag vs slot-index, only use as many bits as necessary for the slot-index (based on the number of slots in the pool), and the remaining bits for the unique-tag

sokol_app.h planned features:

Mainly some "missing features" for desktop apps:

• 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)

sokol_audio.h planned features:

• implement an alternative WebAudio backend using Audio Worklets and WASM threads

Updates

• 08-Sep-2019: sokol_gfx.h now supports clamp-to-border texture sampling:

  • the enum sg_wrap has a new member SG_WRAP_CLAMP_TO_BORDER
  • there's a new enum sg_border_color
  • the struct sg_image_desc has a new member sg_border_color border_color
  • new feature flag in sg_features: image_clamp_to_border

  Note the following caveats:

  • clamp-to-border is only supported on a subset of platforms, support can be checked at runtime via sg_query_features().image_clamp_to_border (D3D11, desktop-GL and macOS-Metal support clamp-to-border, all other platforms don't)
  • there are three hardwired border colors: transparent-black, opaque-black and opaque-white (modern 3D APIs have moved away from a freely programmable border color)
  • if clamp-to-border is not supported, sampling will fall back to clamp-to-edge without a validation warning

  Many thanks to @martincohen for suggesting the feature and providing the initial D3D11 implementation!

• 31-Aug-2019: The header sokol_gfx_cimgui.h has been merged into sokol_gfx_imgui.h. Same idea as merging sokol_cimgui.h into sokol_imgui.h, the implementation is now "bilingual", and can either be included into a C++ file or into a C file. When included into a C++ file, the Dear ImGui C++ API will be called directly, otherwise the C API bindings via cimgui.h

• 28-Aug-2019: The header sokol_cimgui.h has been merged into sokol_imgui.h. The sokol_cimgui.h header had been created to implement Dear ImGui UIs from pure C applications, instead of having to fall back to C++ just for the UI code. However, there was a lot of code duplication between sokol_imgui.h and sokol_cimgui.h, so that it made more sense to merge the two headers. The C vs C++ code path will be selected automatically: When the implementation of sokol_imgui.h is included into a C++ source file, the Dear ImGui C++ API will be used. Otherwise, when the implementation is included into a C source file, the C API via cimgui.h

• 27-Aug-2019: sokol_audio.h now has an OpenSLES backend for Android. Many thanks to Sepehr Taghdisian (@septag) for the PR!

• 26-Aug-2019: new utility header for text rendering, and fixes in sokol_gl.h:

  • a new utility header sokol_fontstash.h which implements a renderer for fontstash.h on top of sokol_gl.h
  • sokol_gl.h updates:
    • Optimization: If no relevant state between two begin/end pairs has changed, draw commands will be merged into a single sokol-gfx draw call. This is especially useful for text- and sprite-rendering (previously, each begin/end pair would always result in one draw call).
    • Bugfix: When calling sgl_disable_texture() the previously active texture would still remain active which could lead to rendering artefacts. This has been fixed.
    • Feature: It's now possible to provide a custom shader in the 'desc' argument of sgl_make_pipeline(), as long as the shader is "compatible" with sokol_gl.h, see the sokol_fontstash.h header for an example. This feature isn't "advertised" in the sokol_gl.h documentation because it's a bit brittle (for instance if sokol_gl.h updates uniform block structures, custom shaders would break), but it may still come in handy in some situations.

• 20-Aug-2019: sokol_gfx.h has a couple new query functions to inspect the default values of resource-creation desc structures:

  sg_buffer_desc sg_query_buffer_defaults(const sg_buffer_desc* desc);
  sg_image_desc sg_query_image_defaults(const sg_image_desc* desc);
  sg_shader_desc sg_query_shader_defaults(const sg_shader_desc* desc);
  sg_pipeline_desc sg_query_pipeline_defaults(const sg_pipeline_desc* desc);
  sg_pass_desc sg_query_pass_defaults(const sg_pass_desc* desc);
  

  These functions take a pointer to a resource creation desc struct that may contain zero-initialized values (to indicate default values) and return a new struct where the zero-init values have been replaced with concrete values. This is useful to inspect the actual creation attributes of a resource.

• 18-Aug-2019:

  • Pixelformat and runtime capabilities modernization in sokol_gfx.h (breaking changes):
    • The list of pixel formats supported in sokol_gfx.h has been modernized, many new formats are available, and some formats have been removed. The supported pixel formats are now identical with what WebGPU provides, minus the SRGB formats (if SRGB conversion is needed it should be done in the pixel shader)
    • The pixel format list is now more "orthogonal":
      • one, two or four color components (R, RG, RGBA)
      • 8-, 16- or 32-bit component width
      • unsigned-normalized (no postfix), signed-normalized (SN postfix), unsigned-integer (UI postfix) and signed-integer (SI postfix) and float (F postfix) component types.
      • special pixel formats BGRA8 (default render target format on Metal and D3D11), RGB10A2 and RG11B10F
      • DXT compressed formats replaced with BC1 to BC7 (BC1 to BC3 are identical to the old DXT pixel formats)
      • packed 16-bit formats (like RGBA4) have been removed
      • packed 24-bit formats (RGB8) have been removed
    • Use the new function sg_query_pixelformat() to get detailed runtime capability information about a pixelformat (for instance whether it is supported at all, can be used as render target etc...).
    • Use the new function sg_query_limits() to query "numeric limits" like maximum texture dimensions for different texture types.
    • The enumeration sg_feature and the function sg_query_feature() has been replaced with the new function sg_query_features(), which returns a struct sg_features (this contains a bool for each optional feature).
    • The default pixelformat for render target images and pipeline objects now depends on the backend:
      • for GL backends, the default pixelformat stays the same: RGBA8
      • for the Metal and D3D11 backends, the default pixelformat for render target images is now BGRA8 (the reason is because MTKView's pixelformat was always BGRA8 but this was "hidden" through an internal hack, and a BGRA swapchain is more efficient than RGBA in D3D11/DXGI)
    • Because of the above RGBA/BGRA change, you may see pixelformat validation errors in existing code if the code assumes that a render target image is always created with a default pixelformat of RGBA8.
  • Changes in sokol_app.h:
    • The D3D11 backend now creates the DXGI swapchain with BGRA8 pixelformat (previously: RGBA8), this allows more efficient presentation in some situations since no format-conversion-blit needs to happen.

• 18-Jul-2019:

  • sokol_fetch.h has been fixed and can be used again :)

• 11-Jul-2019:

  • Don't use sokol_fetch.h for now, the current version assumes that it is possible to obtain the content size of a file from the HTTP server without downloading the entire file first. Turns out that's not possible with vanilla HTTP when the web server serves files compressed (in that case the Content-Length is the compressed size, yet JS/WASM only has access to the uncompressed data). Long story short, I need to go back to the drawing board :)

• 06-Jul-2019:

  • new header sokol_fetch.h for asynchronously loading data.
    • make sure to carefully read the embedded documentation for making the best use of the header
    • two new samples: simple PNG file loadng with stb_image.h and MPEG1 streaming with pl_mpeg.h
  • sokol_gfx.h: increased SG_MAX_SHADERSTAGE_BUFFERS configuration constant from 4 to 8.

• 10-Jun-2019: sokol_app.h now has proper "application quit handling":

  • a pending quit can be intercepted, for instance to show a "Really Quit?" dialog box
  • application code can now initiate a "soft quit" (interceptable) or "hard quit" (not interceptable)
  • on the web platform, the standard "Leave Site?" dialog box implemented by browsers can be shown when the user leaves the site
  • Android and iOS currently don't have any of those features (since the operating system may decide to terminate mobile applications at any time anyway, if similar features are added they will most likely have similar limitations as the web platform) For details, search for 'APPLICATION QUIT' in the sokol_app.h documentation header: https://github.com/floooh/sokol/blob/master/sokol_app.h

  The imgui-highdpi-sapp contains sample code for all new quit-related features.

• 08-Jun-2019: some new stuff in sokol_app.h:

  • the sapp_event struct has a new field bool key_repeat which is true when a keyboard event is a key-repeat (for the event types SAPP_EVENTTYPE_KEY_DOWN and SAPP_EVENTTYPE_CHAR). Many thanks to Scott Lembcke for the pull request!
  • a new function to poll the internal frame counter: uint64_t sapp_frame_count(void), previously the frame counter was only available via sapp_event.
  • also check out the new event-inspector sample

• 04-Jun-2019: All sokol headers now recognize a config-define SOKOL_DLL if sokol should be compiled into a DLL (when used with SOKOL_IMPL) or used as a DLL. On Windows, this will prepend the public function declarations with __declspec(dllexport) or __declspec(dllimport).

• 31-May-2019: if you're working with emscripten and fips, please note the following changes:

  https://github.com/floooh/fips#public-service-announcements

• 27-May-2019: some D3D11 updates:

  • The shader-cross-compiler can now generate D3D bytecode when running on Windows, see the sokol-shdc docs for more details.
  • sokol_gfx.h no longer needs to be compiled with a SOKOL_D3D11_SHADER_COMPILER define to enable shader compilation in the D3D11 backend. Instead, the D3D shader compiler DLL (d3dcompiler_47.dll) will be loaded on-demand when the first HLSL shader needs to be compiled. If an application only uses D3D shader byte code, the compiler DLL won't be loaded into the process.

• 24-May-2019 The shader-cross-compiler can now generate Metal byte code for macOS or iOS when the build is running on macOS. This is enabled automatically with the fips-integration files in sokol-tools-bin, see the sokol-shdc docs for more details.

• 16-May-2019 two new utility headers: sokol_cimgui.h and sokol_gfx_cimgui.h, those are the same as their counterparts sokol_imgui.h and sokol_gfx_imgui.h, but use the cimgui C-API for Dear ImGui. This is useful if you don't want to - or cannot - use C++ for creating Dear ImGui UIs.

  Many thanks to @prime31 for contributing those!

  sokol_cimgui.h is used here, and sokol_gfx_cimgui.h is used for the debugging UI here

• 15-May-2019 there's now an optional shader-cross-compiler solution for sokol_gfx.h: see here for details. This is "V1.0" with two notable features missing:

  • an include-file feature for GLSL shaders
  • compilation to Metal- and D3D-bytecode (currently only source-code generation is supported)

  The sokol-app samples have been ported to the new shader-cross-compilation, follow the src and glsl links on the specific sample webpages to see the C- and GLSL- source-code.

• 02-May-2019 sokol_gfx.h has a new function sg_query_backend(), this will return an enum sg_backend identifying the backend sokol-gfx is currently running on, which is one of the following values:

  • SG_BACKEND_GLCORE33
  • SG_BACKEND_GLES2
  • SG_BACKEND_GLES3
  • SG_BACKEND_D3D11
  • SG_BACKEND_METAL_MACOS
  • SG_BACKEND_METAL_IOS

  When compiled with SOKOL_GLES3, sg_query_backend() may return SG_BACKEND_GLES2 when the runtime platform doesn't support GLES3/WebGL2 and had to fallback to GLES2/WebGL2.

  When compiled with SOKOL_METAL, sg_query_backend() will return SG_BACKEND_METAL_MACOS when the compile target is macOS, and SG_BACKEND_METAL_IOS when the target is iOS.

• 26-Apr-2019 Small but breaking change in sokol_gfx.h how the vertex layout definition in sg_pipeline_desc works:

  Vertex component names and semantics (needed by the GLES2 and D3D11 backends) have moved from sg_pipeline_desc into sg_shader_desc.

  This may seem like a rather pointless small detail to change, expecially for breaking existing code, but the whole thing will make a bit more sense when the new shader-cross-compiler will be integrated which I'm currently working on (here: https://github.com/floooh/sokol-tools).

  While working on getting reflection data out of the shaders (e.g. what uniform blocks and textures the shader uses), it occurred to me that vertex-attribute-names and -semantics are actually part of the reflection info and belong to the shader, not to the vertex layout in the pipeline object (which only describes how the incoming vertex data maps to vertex-component slots. Instead of (optionally) mapping this association through a name, the pipeline's vertex layout is now always strictly defined in terms of numeric 'bind slots' for all sokol_gfx.h backends. For 3D APIs where the vertex component slot isn't explicitely defined in the shader language (GLES2/WebGL, D3D11, and optionally GLES3/GL), the shader merely offers a lookup table how vertex-layout slot-indices map to names/semantics (and the underlying 3D API than maps those names back to slot indices, which shows that Metal and GL made the right choice defining the slots right in the shader).

  Here's how the code changes (taken from the triangle-sapp.c sample):

  OLD:

  /* create a shader */
  sg_shader shd = sg_make_shader(&(sg_shader_desc){
      .vs.source = vs_src,
      .fs.source = fs_src,
  });
  
  /* create a pipeline object (default render states are fine for triangle) */
  pip = sg_make_pipeline(&(sg_pipeline_desc){
      /* if the vertex layout doesn't have gaps, don't need to provide strides and offsets */
      .shader = shd,
      .layout = {
          .attrs = {
              [0] = { .name="position", .sem_name="POS", .format=SG_VERTEXFORMAT_FLOAT3 },
              [1] = { .name="color0", .sem_name="COLOR", .format=SG_VERTEXFORMAT_FLOAT4 }
          }
      },
  });
  

  NEW:

      /* create a shader */
      sg_shader shd = sg_make_shader(&(sg_shader_desc){
          .attrs = {
              [0] = { .name="position", .sem_name="POS" },
              [1] = { .name="color0", .sem_name="COLOR" }
          },
          .vs.source = vs_src,
          .fs.source = fs_src,
      });
  
      /* create a pipeline object (default render states are fine for triangle) */
      pip = sg_make_pipeline(&(sg_pipeline_desc){
          /* if the vertex layout doesn't have gaps, don't need to provide strides and offsets */
          .shader = shd,
          .layout = {
              .attrs = {
                  [0].format=SG_VERTEXFORMAT_FLOAT3,
                  [1].format=SG_VERTEXFORMAT_FLOAT4
              }
          },
      });
  

  sg_shader_desc has a new embedded struct attrs which contains a vertex attribute name (for GLES2/WebGL) and sem_name/sem_index (for D3D11). For the Metal backend this struct is ignored completely, and for GLES3/GL it is optional, and not required when the vertex shader inputs are annotated with layout(location=N).

  The remaining attribute description members in sg_pipeline_desc are:

  • .format: the format of input vertex data (this can be different from the vertex shader's inputs when data is extended during vertex fetch (e.g. input can be vec3 while the vertex shader expects vec4)
  • .offset: optional offset of the vertex component data (not needed when the input vertex has no gaps between the components)
  • .buffer: the vertex buffer bind slot if the vertex data is coming from different buffers

  Also check out the various samples:

  • for GLSL (explicit slots via layout(location=N)): https://github.com/floooh/sokol-samples/tree/master/glfw
  • for D3D11 (semantic names/indices): https://github.com/floooh/sokol-samples/tree/master/d3d11
  • for GLES2: (vertex attribute names): https://github.com/floooh/sokol-samples/tree/master/html5
  • for Metal: (explicit slots): https://github.com/floooh/sokol-samples/tree/master/metal
  • ...and all of the above combined: https://github.com/floooh/sokol-samples/tree/master/sapp

• 19-Apr-2019 I have replaced the rather inflexible render-state handling in sokol_gl.h with a pipeline stack (like the GL matrix stack, but with pipeline-state-objects), along with a couple of other minor API tweaks.

  These are the new pipeline-stack functions:

  sgl_pipeline sgl_make_pipeline(const sg_pipeline_desc* desc);
  void sgl_destroy_pipeline(sgl_pipeline pip);
  void sgl_default_pipeline(void);
  void sgl_load_pipeline(sgl_pipeline pip);
  void sgl_push_pipeline(void);
  void sgl_pop_pipeline(void);
  

  A pipeline object is created just like in sokol_gfx.h, but without shaders, vertex layout, pixel formats, primitive-type and sample count (these details are filled in by the sgl_make_pipeline() wrapper function. For instance to create a pipeline object for additive transparency:

  sgl_pipeline additive_pip = sgl_make_pipeline(&(sg_pipeline_desc){
      .blend = {
          .enabled = true,
          .src_factor_rgb = SG_BLENDFACTOR_ONE,
          .dst_factor_rgb = SG_BLENDFACTOR_ONE
      }
  });
  

  And to render with this, simply call sgl_load_pipeline():

  sgl_load_pipeline(additive_pip);
  sgl_begin_triangles();
  ...
  sgl_end();
  

  Or to preserve and restore the previously active pipeline state:

  sgl_push_pipeline();
  sgl_load_pipeline(additive_pip);
  sgl_begin_quads();
  ...
  sgl_end();
  sgl_pop_pipeline();
  

  You can also load the 'default pipeline' explicitely on the top of the pipeline stack with sgl_default_pipeline().

  The other API change is:

  • sgl_state_texture(bool b) has been replaced with sgl_enable_texture() and sgl_disable_texture()

  The code samples have been updated accordingly:

  • sgl-sapp.c
  • sgl-lines-sapp.c
  • sgl-microui-sapp.c

• 01-Apr-2019 (not an April Fool's joke): There's a new sokol_gl.h util header which implements an 'OpenGL-1.x-in-spirit' rendering API on top of sokol_gfx.h (vertex specification via begin/end, and a matrix stack). This is only a small subset of OpenGL 1.x, mainly intended for debug-visualization or simple tasks like 2D UI rendering. As always, sample code is in the sokol-samples project.

• 15-Mar-2019: various Dear ImGui related changes:

  • there's a new utility header sokol_imgui.h with a simple drop-in renderer for Dear ImGui on top of sokol_gfx.h and sokol_app.h (sokol_app.h is optional, and only used for input handling)
  • the sokol_gfx_imgui.h debug inspection header no longer depends on internal data structures and functions of sokol_gfx.h, as such it is now a normal utility header and has been moved to the utils directory
  • the implementation macro for sokol_gfx_imgui.h has been changed from SOKOL_IMPL to SOKOL_GFX_IMGUI_IMPL (so when you suddenly get unresolved linker errors, that's the reason)
  • all headers now have two preprocessor defines for the declaration and implementation (for instance in sokol_gfx.h: SOKOL_GFX_INCLUDED and SOKOL_GFX_IMPL_INCLUDED) these are checked in the utility-headers to provide useful error message when dependent headers are missing

• 05-Mar-2019: sokol_gfx.h now has a 'trace hook' API, and I have started implementing optional debug-inspection-UI headers on top of Dear ImGui:

  • sokol_gfx.h has a new function sg_install_trace_hooks(), this allows you to install a callback function for each public sokol_gfx.h function (and a couple of error callbacks). For more details, search for "TRACE HOOKS" in sokol_gfx.h
  • when creating sokol_gfx.h resources, you can now set a 'debug label' in the desc structure, this is ignored by sokol_gfx.h itself, but is useful for debuggers or profilers hooking in via the new trace hooks
  • likewise, two new functions sg_push_debug_group() and sg_pop_debug_group() can be used to group related drawing functions under a name, this is also ignored by sokol_gfx.h itself and only useful when hooking into the API calls
  • I have started a new 'subproject' in the 'imgui' directory, this will contain a slowly growing set of optional debug-inspection-UI headers which allow to peek under the hood of the Sokol headers. The UIs are implemented with Dear ImGui. Again, see the README in the 'imgui' directory and the headers in there for details, and check out the live demos on the Sokol Sample Webpage (click on the little UI buttons in the top right corner of each thumbnail)

• 21-Feb-2019: sokol_app.h and sokol_audio.h now have an alternative set of callbacks with user_data arguments. This is useful if you don't want or cannot store your own application state in global variables. See the header documentation in sokol_app.h and sokol_audio.h for details, and check out the samples sapp/noentry-sapp.c and sapp/modplay-sapp.c in https://github.com/floooh/sokol-samples

• 19-Feb-2019: sokol_app.h now has an alternative mode where it doesn't "hijack" the platform's main() function. Search for SOKOL_NO_ENTRY in sokol_app.h for details and documentation.

• 26-Jan-2019: sokol_app.h now has an Android backend contributed by Gustav Olsson! See the sokol-samples readme for build instructions.

• 21-Jan-2019: sokol_gfx.h - pool-slot-generation-counters and a dummy backend:

  • Resource pool slots now have a generation-counter for the resource-id unique-tag, instead of a single counter for the whole pool. This allows to create many more unique handles.
  • sokol_gfx.h now has a dummy backend, activated by defining SOKOL_DUMMY_BACKEND (instead of SOKOL_METAL, SOKOL_D3D11, ...), this allows to write 'headless' tests (and there's now a sokol-gfx-test in the sokol-samples repository which mainly tests the resource pool system)

• 12-Jan-2019: sokol_gfx.h - setting the pipeline state and resource bindings now happens in separate calls, specifically:

  • sg_apply_draw_state() has been replaced with sg_apply_pipeline() and sg_apply_bindings()
  • the sg_draw_state struct has been replaced with sg_bindings
  • sg_apply_uniform_block() has been renamed to sg_apply_uniforms()

All existing code will still work. See this blog post for details.

• 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!