scripts/gen-gl-loader.sh — sigil-graphics

1#!/bin/sh

2# gen-gl-loader.sh - regenerate src/c/gl_native_loader.h from vendor/sokol/sokol_gfx.h

3#

4# sokol_gfx's GL backend either includes the system GL headers (and links

5# libGL) or, on Win32, carries its own loader: GL types, constants and an

6# X-macro list of every GL function it calls. This script lifts those two

7# blocks out of the vendored header and emits a loader that fills the same

8# function pointers through a caller-supplied proc loader

9# (sigil_desktop_gl_get_proc_address, i.e. glfwGetProcAddress). The result

10# is what SOKOL_EXTERNAL_GL_LOADER expects on every native target, so no

11# GL header is needed to build and no libGL is linked.

12#

13# Run after every sokol_gfx.h bump; the counts below refuse a header whose

14# shape moved. Anchors are patterns, and each extraction is guarded by a

15# line count so a silent no-match cannot produce an empty header.

16set -eu

17cd "$(dirname "$0")/.."

18SRC=vendor/sokol/sokol_gfx.h

19OUT=src/c/gl_native_loader.h

20T=$(mktemp -d); trap 'rm -rf "$T"' EXIT

22# 1. the types + constants block: from the first GL typedef after

23# "#define GL_APIENTRY APIENTRY" to the "#endif" that closes the

24# win32-loader-definitions block

25awk '

26 /#define GL_APIENTRY APIENTRY/ { armed = 1; next }

27 armed && !started && /typedef unsigned int GLenum;/ { started = 1 }

28 started && /^ #endif/ { exit }

29 started { sub(/^ /, ""); print }

30' "$SRC" > "$T/defs.h"

31N1=$(wc -l < "$T/defs.h")

[ "$N1" -gt 200 ] && [ "$N1" -lt 400 ] || { echo "REFUSING: types+constants block is $N1 lines (expected 200..400)"; exit 1; }

33grep -q '^typedef unsigned int GLenum;' "$T/defs.h" || { echo "REFUSING: no GLenum typedef"; exit 1; }

tail -1 "$T/defs.h" | grep -q "^#define GL_MAX_IMAGE_UNITS " || { echo "REFUSING: constants block does not end on GL_MAX_IMAGE_UNITS (got: $(tail -1 "$T/defs.h"))"; exit 1; }

36# 2. the X-macro list: the body of _SG_GL_FUNCS, minus the SG_GL_FUNCS_EXT hook

37awk '

38 /^#define _SG_GL_FUNCS \\$/ { started = 1; next }

39 started && /SG_GL_FUNCS_EXT/ { next }

40 started { print; if ($0 !~ /\\$/) exit }

41' "$SRC" | sed 's/_SG_XMACRO(/SIGIL_GL_XMACRO(/' > "$T/funcs.h"

42N2=$(grep -c 'SIGIL_GL_XMACRO(' "$T/funcs.h")

[ "$N2" -gt 100 ] && [ "$N2" -lt 200 ] || { echo "REFUSING: function list has $N2 entries (expected 100..200)"; exit 1; }

grep -q 'SIGIL_GL_XMACRO(glGenBuffers,' "$T/funcs.h" || { echo "REFUSING: glGenBuffers not in the function list"; exit 1; }

45# the last line must not end in a backslash (the macro closes there)

46tail -1 "$T/funcs.h" | grep -q '\\$' && { echo "REFUSING: function list did not close"; exit 1; }

48{

49cat <<HDR

50/*

51 * gl_native_loader.h - GL types, constants and entry points for sokol_gfx

52 * without a system GL header or a libGL link.

53 *

54 * GENERATED by scripts/gen-gl-loader.sh from vendor/sokol/sokol_gfx.h

55 * (sokol's own Win32 loader block); do not edit, regenerate after a sokol

56 * bump. Included once, by sokol-graphics.c, ahead of sokol_gfx.h with

57 * SOKOL_EXTERNAL_GL_LOADER defined. Every gl* sokol_gfx calls is a static

58 * function pointer here, filled by sigil_gl_load() through a proc loader

59 * (sigil_desktop_gl_get_proc_address, GLFW's glfwGetProcAddress) once the

60 * window's GL context is current. $N2 functions, $N1 lines of definitions.

61 */

62#ifndef SIGIL_GL_NATIVE_LOADER_H

63#define SIGIL_GL_NATIVE_LOADER_H

65#include <stddef.h>

66#include <stdint.h>

68/* sokol_gfx picks its Apple feature set from TargetConditionals.h, which it

69 * includes itself only when it also includes the system GL headers; with

70 * an external loader that is this header's job, or macOS would be read as

71 * iOS (no base-vertex draws). */

72#if defined(__APPLE__)

73#include <TargetConditionals.h>

74#endif

76#if defined(_WIN32) && !defined(_WIN64)

77#define GL_APIENTRY __stdcall

78#else

79#define GL_APIENTRY

80#endif

82/* The guards the system GL headers use, so a later include of any of them

83 * (glfw3.h without GLFW_INCLUDE_NONE, say) defines nothing twice. */

84#define __gl_h_ 1

85#define __gl32_h_ 1

86#define __gl31_h_ 1

87#define __GL_H__ 1

88#define __glext_h_ 1

89#define __GLEXT_H_ 1

90#define __gltypes_h_ 1

91#define __glcorearb_h_ 1

92#define __gl_glcorearb_h_ 1

94/* sokol_gfx enables its 3.2 / 4.2 / 4.3 code paths on these, as the system

95 * headers (Mesa's glext.h) defined them before; the runtime check on the

96 * context's reported version still gates their use. */

97#define GL_VERSION_3_2 1

98#define GL_VERSION_4_2 1

99#define GL_VERSION_4_3 1

100

101/* ---- types and constants (from sokol_gfx.h) ---- */

102HDR

103cat "$T/defs.h"

104cat <<MID

105

106/* ---- the entry points sokol_gfx calls (from sokol_gfx.h) ---- */

107#define SIGIL_GL_FUNCS \\

108MID

109cat "$T/funcs.h"

110cat <<'FTR'

111

112#define SIGIL_GL_XMACRO(name, ret, args) typedef ret (GL_APIENTRY* PFN_ ## name) args;

113SIGIL_GL_FUNCS

114#undef SIGIL_GL_XMACRO

115

116#define SIGIL_GL_XMACRO(name, ret, args) static PFN_ ## name name;

117SIGIL_GL_FUNCS

118#undef SIGIL_GL_XMACRO

119

120typedef void *(*sigil_gl_proc_loader)(const char *name);

121

122/* Fill every pointer through `load`. Returns the number left NULL: entry

123 * points newer than the context (glTextureView on a 4.1 context, the

124 * base-instance draws before 4.2) are expected to be missing and sokol_gfx

125 * only calls them behind its feature checks; glGenBuffers or glGetIntegerv

126 * missing means there is no usable context, and sigil_gl_ready() says so. */

127static int sigil_gl_load(sigil_gl_proc_loader load)

128{

129 int missing = 0;

130#define SIGIL_GL_XMACRO(name, ret, args) \

131 name = (PFN_ ## name)load(#name); if (!name) missing++;

132 SIGIL_GL_FUNCS

133#undef SIGIL_GL_XMACRO

134 return missing;

135}

136

137static int sigil_gl_ready(void)

138{

139 return glGetIntegerv != NULL && glClearBufferfv != NULL && glGenBuffers != NULL

140 && glCreateShader != NULL && glBindFramebuffer != NULL;

141}

142

143#endif /* SIGIL_GL_NATIVE_LOADER_H */

144FTR

145} > "$OUT"

146echo "wrote $OUT: $N1 definition lines, $N2 functions, $(wc -l < "$OUT") lines total"