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inject the missing packing/unpacking function in ESSL 3.0
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FIXES=[343784713]
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@pixelflinger
pixelflinger committed Jun 18, 2024
1 parent cab799f commit e04c6d4
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Showing 2 changed files with 91 additions and 11 deletions.
100 changes: 90 additions & 10 deletions filament/backend/src/opengl/ShaderCompilerService.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -572,16 +572,23 @@ void ShaderCompilerService::compileShaders(OpenGLContext& context,

// split shader source, so we can insert the specialization constants and the packing
// functions
auto const [prolog, body] = splitShaderSource({ shader_src, shader_len });
auto [version, prolog, body] = splitShaderSource({ shader_src, shader_len });

const std::array<const char*, 4> sources = {
// enable ESSL 3.10 if available
if (context.isAtLeastGLES<3, 1>()) {
version = "#version 310 es\n";
}

const std::array<const char*, 5> sources = {
version.data(),
prolog.data(),
specializationConstantString.c_str(),
packingFunctions.data(),
body.data()
};

const std::array<GLint, 4> lengths = {
const std::array<GLint, 5> lengths = {
(GLint)version.length(),
(GLint)prolog.length(),
(GLint)specializationConstantString.length(),
(GLint)packingFunctions.length(),
Expand Down Expand Up @@ -661,6 +668,7 @@ void ShaderCompilerService::process_OVR_multiview2(OpenGLContext& context,

// Tragically, OpenGL 4.1 doesn't support unpackHalf2x16 (appeared in 4.2) and
// macOS doesn't support GL_ARB_shading_language_packing
// Also GLES3.0 didn't have the full set of packing/unpacking functions
std::string_view ShaderCompilerService::process_ARB_shading_language_packing(OpenGLContext& context) noexcept {
using namespace std::literals;
#ifdef BACKEND_OPENGL_VERSION_GL
Expand Down Expand Up @@ -700,31 +708,103 @@ highp uint packHalf2x16(vec2 v) {
highp uint y = fp32tou16(v.y);
return (y << 16u) | x;
}
highp uint packUnorm4x8(mediump vec4 v) {
v = round(clamp(v, 0.0, 1.0) * 255.0);
highp uint a = uint(v.x);
highp uint b = uint(v.y) << 8;
highp uint c = uint(v.z) << 16;
highp uint d = uint(v.w) << 24;
return (a|b|c|d);
}
highp uint packSnorm4x8(mediump vec4 v) {
v = round(clamp(v, -1.0, 1.0) * 127.0);
highp uint a = uint((int(v.x) & 0xff));
highp uint b = uint((int(v.y) & 0xff)) << 8;
highp uint c = uint((int(v.z) & 0xff)) << 16;
highp uint d = uint((int(v.w) & 0xff)) << 24;
return (a|b|c|d);
}
mediump vec4 unpackUnorm4x8(highp uint v) {
return vec4(float((v & 0x000000ffu) ),
float((v & 0x0000ff00u) >> 8),
float((v & 0x00ff0000u) >> 16),
float((v & 0xff000000u) >> 24)) / 255.0;
}
mediump vec4 unpackSnorm4x8(highp uint v) {
int a = int(((v ) & 0xffu) << 24u) >> 24 ;
int b = int(((v >> 8u) & 0xffu) << 24u) >> 24 ;
int c = int(((v >> 16u) & 0xffu) << 24u) >> 24 ;
int d = int(((v >> 24u) & 0xffu) << 24u) >> 24 ;
return clamp(vec4(float(a), float(b), float(c), float(d)) / 127.0, -1.0, 1.0);
}
)"sv;
}
#endif // BACKEND_OPENGL_VERSION_GL

#ifdef BACKEND_OPENGL_VERSION_GLES
if (!context.isES2() && !context.isAtLeastGLES<3, 1>()) {
return R"(
highp uint packUnorm4x8(mediump vec4 v) {
v = round(clamp(v, 0.0, 1.0) * 255.0);
highp uint a = uint(v.x);
highp uint b = uint(v.y) << 8;
highp uint c = uint(v.z) << 16;
highp uint d = uint(v.w) << 24;
return (a|b|c|d);
}
highp uint packSnorm4x8(mediump vec4 v) {
v = round(clamp(v, -1.0, 1.0) * 127.0);
highp uint a = uint((int(v.x) & 0xff));
highp uint b = uint((int(v.y) & 0xff)) << 8;
highp uint c = uint((int(v.z) & 0xff)) << 16;
highp uint d = uint((int(v.w) & 0xff)) << 24;
return (a|b|c|d);
}
mediump vec4 unpackUnorm4x8(highp uint v) {
return vec4(float((v & 0x000000ffu) ),
float((v & 0x0000ff00u) >> 8),
float((v & 0x00ff0000u) >> 16),
float((v & 0xff000000u) >> 24)) / 255.0;
}
mediump vec4 unpackSnorm4x8(highp uint v) {
int a = int(((v ) & 0xffu) << 24u) >> 24 ;
int b = int(((v >> 8u) & 0xffu) << 24u) >> 24 ;
int c = int(((v >> 16u) & 0xffu) << 24u) >> 24 ;
int d = int(((v >> 24u) & 0xffu) << 24u) >> 24 ;
return clamp(vec4(float(a), float(b), float(c), float(d)) / 127.0, -1.0, 1.0);
}
)"sv;
}
#endif // BACKEND_OPENGL_VERSION_GLES
return ""sv;
}

// split shader source code in two, the first section goes from the start to the line after the
// last #extension, and the 2nd part goes from there to the end.
std::array<std::string_view, 2> ShaderCompilerService::splitShaderSource(std::string_view source) noexcept {
// split shader source code in three:
// - the version line
// - extensions
// - everything else
std::array<std::string_view, 3> ShaderCompilerService::splitShaderSource(std::string_view source) noexcept {
auto start = source.find("#version");
assert_invariant(start != std::string_view::npos);

auto version_eol = source.find('\n', start) + 1;
assert_invariant(version_eol != std::string_view::npos);

auto pos = source.rfind("\n#extension");
if (pos == std::string_view::npos) {
pos = start;
pos = version_eol;
} else {
++pos;
}

auto eol = source.find('\n', pos) + 1;
assert_invariant(eol != std::string_view::npos);

std::string_view const version = source.substr(start, eol - start);
std::string_view const body = source.substr(version.length(), source.length() - version.length());
return { version, body };
std::string_view const version = source.substr(start, version_eol - start);
std::string_view const prolog = source.substr(version_eol, eol - version_eol);
std::string_view const body = source.substr(eol, source.length() - eol);
return { version, prolog, body };
}

/*
Expand Down
2 changes: 1 addition & 1 deletion filament/backend/src/opengl/ShaderCompilerService.h
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Original file line number Diff line number Diff line change
Expand Up @@ -146,7 +146,7 @@ class ShaderCompilerService {

static std::string_view process_ARB_shading_language_packing(OpenGLContext& context) noexcept;

static std::array<std::string_view, 2> splitShaderSource(std::string_view source) noexcept;
static std::array<std::string_view, 3> splitShaderSource(std::string_view source) noexcept;

static GLuint linkProgram(OpenGLContext& context,
std::array<GLuint, Program::SHADER_TYPE_COUNT> shaders,
Expand Down

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