graphics: cond-expand sokol_app/glue seam for a web (wasm32-wasi) target

Message

Milestone 2 of graphics-on-web: let sigil-graphics reuse sokolgfx/sokolgp in the browser via the sigil-wasm-gles3 raw-GLES3 binding, WITHOUT disturbing the native build. The seam is gated on wasm (predefined by the wasm target), so native (SOKOLGLCORE + sokolapp + sigil-app) is byte-for-byte behaviour-identical.

sokol-graphics.c: on web define nothing extra here but include glshim.h (from sigil-wasm-gles3) before sokolgfx.h so every gl* resolves to a WASM import in the "gl" module; drop sokolapp.h / sokolglue.h (no windowing on web); provide slog_func (sigil-app is not linked on web). Native branch unchanged.

graphics.c: route the six sokolapp / sokolglue touch points (sgsetup environment, begin-frame window size, end-frame swapchain, clear fallback size, shader resolution uniform) through a siggfx* abstraction. Native expands to the exact sapp/sglue_ calls as before; web supplies a manual default-framebuffer sgenvironment/sgswapchain (lifted from the M1 wasm-sokol-sprite example) and sources the canvas size from the sigilwasmgles3 app-shell import module.

Verified: all five sigil-graphics C files compile clean for wasm32-wasi (web path) and native graphics.c compiles unchanged; the native diff is limited to behaviour-preserving inline wrappers.

Changed

 src/c/graphics.c       | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 src/c/sokol-graphics.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 108 insertions(+), 18 deletions(-)

Diff

src/c/graphics.cmodified

@@ -6,10 +6,20 @@

#include "sigil-internal.h"

−9

/* Sokol headers (implementation is in sokol.c) */

/* Sokol headers (implementation is in sokol-graphics.c).

+10

*

+11

* On web (wasm32-wasi) there is no windowing system: sokol_app / sokol_glue are

+12

* replaced by the sigil-wasm-gles3 JS bridge (canvas + WebGL2 context +

+13

* swapchain). Those two headers are therefore excluded on the web build; every

+14

* sapp / sglue touch point is routed through the sig_gfx_ abstraction below,

+15

* whose native branch expands to the exact same calls as before. */

+16

#if !defined(__wasm__)

#include "sokol_app.h"

+18

#endif

#include "sokol_gfx.h"

+20

#if !defined(__wasm__)

#include "sokol_glue.h"

+22

#endif

#include "sokol_gp.h"

#include "sokol_log.h"

@@ -19,6 +29,46 @@

#include <string.h>

#include <math.h>

#include <time.h>

+32

#include <stdint.h>

+33

+34

/* ---- platform abstraction: native (sokol_app/glue) vs web (GL bridge) -------

+35

* These four accessors are the ONLY sokol_app/sokol_glue touch points in this

+36

* file. Native expands to the exact sapp / sglue calls used before, so the

+37

* native build is behaviour-identical. Web supplies the default framebuffer

+38

* swapchain manually (lifted from the Milestone-1 wasm-sokol-sprite example) and

+39

* sources the canvas size from the sigil_wasm_gles3 app-shell import module. */

+40

#if defined(__wasm__)

+41

__attribute__((import_module("sigil_wasm_gles3"), import_name("canvas_width")))

+42

extern int sigil_wasm_gles3_canvas_width(void);

+43

__attribute__((import_module("sigil_wasm_gles3"), import_name("canvas_height")))

+44

extern int sigil_wasm_gles3_canvas_height(void);

+45

+46

static int sig_gfx_width(void) { return sigil_wasm_gles3_canvas_width(); }

+47

static int sig_gfx_height(void) { return sigil_wasm_gles3_canvas_height(); }

+48

+49

static sg_environment sig_gfx_environment(void) {

+50

sg_environment env = {0};

+51

env.defaults.color_format = SG_PIXELFORMAT_RGBA8;

+52

env.defaults.depth_format = SG_PIXELFORMAT_NONE;

+53

env.defaults.sample_count = 1;

+54

return env;

+55

}

+56

static sg_swapchain sig_gfx_swapchain(void) {

+57

sg_swapchain swap = {0};

+58

swap.width = sig_gfx_width();

+59

swap.height = sig_gfx_height();

+60

swap.sample_count = 1;

+61

swap.color_format = SG_PIXELFORMAT_RGBA8;

+62

swap.depth_format = SG_PIXELFORMAT_NONE;

+63

swap.gl.framebuffer = 0; /* default framebuffer */

+64

return swap;

+65

}

+66

#else

+67

static inline int sig_gfx_width(void) { return sapp_width(); }

+68

static inline int sig_gfx_height(void) { return sapp_height(); }

+69

static inline sg_environment sig_gfx_environment(void) { return sglue_environment(); }

+70

static inline sg_swapchain sig_gfx_swapchain(void) { return sglue_swapchain(); }

+71

#endif

#ifndef M_PI

#define M_PI 3.14159265358979323846

@@ -183,7 +233,7 @@ static Value native_gfx_setup(SigilVM *vm, int argc, Value *args)

233

/* Initialize sokol_gfx. Install slog_func so validation failures

234

* print a useful diagnostic before sokol aborts. */

235

sg_desc desc = {

−186

.environment = sglue_environment(),

+236

.environment = sig_gfx_environment(),

237

.logger.func = slog_func,

238

};

239

sg_setup(&desc);

@@ -284,8 +334,8 @@ static Value native_begin_frame(SigilVM *vm, int argc, Value *args)

334

{

335

(void)vm; (void)argc; (void)args;

336

−287

int window_w = sapp_width();

−288

int window_h = sapp_height();

+337

int window_w = sig_gfx_width();

+338

int window_h = sig_gfx_height();

339

340

/* Begin sokol_gp frame with full window size */

341

sgp_begin(window_w, window_h);

@@ -332,7 +382,7 @@ static Value native_end_frame(SigilVM *vm, int argc, Value *args)

382

};

383

sg_pass pass = {

384

.action = pass_action,

−335

.swapchain = sglue_swapchain()

+385

.swapchain = sig_gfx_swapchain()

386

};

387

sg_begin_pass(&pass);

388

@@ -369,7 +419,7 @@ static Value native_clear_screen(SigilVM *vm, int argc, Value *args)

419

if (virtual_viewport_enabled && virtual_width > 0 && virtual_height > 0) {

420

sgp_draw_filled_rect(0, 0, (float)virtual_width, (float)virtual_height);

421

} else {

−372

sgp_draw_filled_rect(0, 0, (float)sapp_width(), (float)sapp_height());

+422

sgp_draw_filled_rect(0, 0, (float)sig_gfx_width(), (float)sig_gfx_height());

423

}

424

425

/* Reset to white for subsequent drawing */

@@ -1687,7 +1737,7 @@ static void apply_active_shader_uniforms(void)

1737

&t, sizeof(t));

1738

}

1739

if (sh->u_resolution_index >= 0) {

−1690

float res[2] = {(float)sapp_width(), (float)sapp_height()};

+1740

float res[2] = {(float)sig_gfx_width(), (float)sig_gfx_height()};

1741

if (virtual_viewport_enabled) {

1742

res[0] = (float)virtual_width;

1743

res[1] = (float)virtual_height;

src/c/sokol-graphics.cmodified

@@ -1,14 +1,58 @@

/*

* sokol-graphics.c - Sokol implementation for sigil-graphics

*

−4

* Implements sokol_gfx, sokol_gp, and sokol_glue.

−5

* sokol_glue bridges sokol_app (from sigil-app) to sokol_gfx.

* Implements sokol_gfx and sokol_gp (and, on native, sokol_glue).

*

−7

* Note: sokol_app.h is included for declarations only (implementation in sigil-app).

−8

* SOKOL_IMPL is only defined for the headers we implement here.

* NATIVE (default): SOKOL_GLCORE. sokol_glue bridges sokol_app (implemented in

* sigil-app) to sokol_gfx; sokol_app.h is included for declarations only, and

* slog_func comes from sigil-app.

*

+10

* WEB (wasm32-wasi, __wasm__): SOKOL_GLES3 + SOKOL_EXTERNAL_GL_LOADER (set via

+11

* the web build's -D flags). sokol's gl* calls resolve to WASM imports in the

+12

* "gl" module via gl_shim.h (shipped by sigil-wasm-gles3). There is no

+13

* sokol_app / sokol_glue on web — the canvas, WebGL2 context, and swapchain come

+14

* from the sigil-wasm-gles3 JS bridge (see graphics.c's sig_gfx_* abstraction),

+15

* so those headers are excluded and slog_func is provided here since sigil-app

+16

* is not linked on web.

*/

−11

/* SOKOL_GLCORE is defined via compiler flags */

+19

/* Bump sgp's uniform-block buffer to 64 floats (256 bytes) so custom shaders

+20

* have room for the auto-uniforms (u_time, u_resolution) plus a reasonable

+21

* budget of caller-set uniforms. The default 8 floats (32 bytes) doesn't even

+22

* fit the auto-uniforms plus a single vec4. */

+23

#define SGP_UNIFORM_CONTENT_SLOTS 64

+24

+25

#if defined(__wasm__)

+26

+27

/* Web: bind every gl* sokol calls as a WASM import in the "gl" module. Must be

+28

* included before sokol_gfx.h so GL types/constants/prototypes are visible. */

+29

#include "gl_shim.h"

+30

+31

#define SOKOL_IMPL

+32

/* Order matters: gfx before gp. No sokol_glue (no sokol_app on web). */

+33

#include "sokol_gfx.h"

+34

#include "sokol_gp.h"

+35

+36

/* slog_func is provided by sigil-app on native; on web sigil-app is not linked,

+37

* so supply it here. Routes to stderr (wasi fd_write -> console) so sokol

+38

* validation failures stay visible without any import beyond gl.* + wasi. */

+39

#include <stdio.h>

+40

#include <stdint.h>

+41

void slog_func(const char* tag, uint32_t log_level, uint32_t log_item_id,

+42

const char* message_or_null, uint32_t line_nr,

+43

const char* filename_or_null, void* user_data) {

+44

(void)log_item_id; (void)user_data;

+45

fprintf(stderr, "sokol[level=%u] %s:%u [%s] %s\n",

+46

log_level,

+47

filename_or_null ? filename_or_null : "?",

+48

line_nr,

+49

tag ? tag : "sokol",

+50

message_or_null ? message_or_null : "");

+51

}

+52

+53

#else

+54

+55

/* Native: SOKOL_GLCORE is defined via compiler flags. */

/* Include sokol_app declarations WITHOUT implementation (implemented in sigil-app) */

#include "sokol_app.h"

@@ -16,12 +60,6 @@

/* Now define SOKOL_IMPL for the headers we implement */

#define SOKOL_IMPL

−19

/* Bump sgp's uniform-block buffer to 64 floats (256 bytes) so custom

−20

* shaders have room for the auto-uniforms (u_time, u_resolution) plus

−21

* a reasonable budget of caller-set uniforms. The default 8 floats

−22

* (32 bytes) doesn't even fit the auto-uniforms plus a single vec4. */

−23

#define SGP_UNIFORM_CONTENT_SLOTS 64

−24

/* Order matters: gfx before glue, glue before gp */

#include "sokol_gfx.h"

#include "sokol_glue.h"

@@ -29,3 +67,5 @@

/* slog_func is implemented in sigil-app's archive (sigil-app's

* sokol-app.c picks up SOKOL_LOG_IMPL via SOKOL_IMPL). graphics.c

* just declares it via sokol_log.h. */

+70

+71

#endif