glslang

You can build glslang from source using CMake. Ensure you have a C++17 compiler, CMake, and make (or ninja) installed. Python 3.x is required if using SPIRV-Tools.

Prerequisites

1. Clone the repository.
2. Run ./update_glslang_sources.py to check out external projects.

Build Steps

Linux:

cmake -B $BUILD_DIR -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
make -j4 install

Windows:

cmake -B $BUILD_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
cmake --build . --config Release --target install

Android: Requires the Android NDK. Use the -DANDROID_TOOLCHAIN=clang and appropriate -DANDROID_ABI flags.

cmake -B $BUILD_DIR -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$(pwd)/install" -DANDROID_ABI=arm64-v8a -DCMAKE_BUILD_TYPE=Release -DANDROID_STL=c++_static -DANDROID_PLATFORM=android-24 -DCMAKE_SYSTEM_NAME=Android -DANDROID_TOOLCHAIN=clang -DANDROID_ARM_MODE=arm -DCMAKE_MAKE_PROGRAM=$ANDROID_NDK_HOME/prebuilt/linux-x86_64/bin/make -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake

The glslang_c_interface.h provides a C-compatible interface similar to the C++ class interface. This is useful for cross-language bindings.

To compile GLSL to SPIR-V 1.5 for Vulkan 1.2, you must populate a glslang_input_t struct, create a shader via glslang_shader_create, preprocess, parse, and then link using a glslang_program_t object.

#include <glslang/Include/glslang_c_interface.h>
#include <glslang/Public/resource_limits_c.h>

typedef struct SpirVBinary {
    uint32_t *words; // SPIR-V words
    int size; // number of words in SPIR-V binary
} SpirVBinary;

SpirVBinary compileShaderToSPIRV_Vulkan(glslang_stage_t stage, const char* shaderSource, const char* fileName) {
    const glslang_input_t input = {
        .language = GLSLANG_SOURCE_GLSL,
        .stage = stage,
        .client = GLSLANG_CLIENT_VULKAN,
        .client_version = GLSLANG_TARGET_VULKAN_1_2,
        .target_language = GLSLANG_TARGET_SPV,
        .target_language_version = GLSLANG_TARGET_SPV_1_5,
        .code = shaderSource,
        .default_version = 100,
        .default_profile = GLSLANG_NO_PROFILE,
        .force_default_version_and_profile = false,
        .forward_compatible = false,
        .messages = GLSLANG_MSG_DEFAULT_BIT,
        .resource = glslang_default_resource(),
    };

    glslang_shader_t* shader = glslang_shader_create(&input);

    SpirVBinary bin = {.words = NULL, .size = 0};
    if (!glslang_shader_preprocess(shader, &input)) {
        // Handle error
        glslang_shader_delete(shader);
        return bin;
    }

    if (!glslang_shader_parse(shader, &input)) {
        // Handle error
        glslang_shader_delete(shader);
        return bin;
    }

    glslang_program_t* program = glslang_program_create();
    glslang_program_add_shader(program, shader);

    if (!glslang_program_link(program, GLSLANG_MSG_SPV_RULES_BIT | GLSLANG_MSG_VULKAN_RULES_BIT)) {
        // Handle error
        glslang_program_delete(program);
        glslang_shader_delete(shader);
        return bin;
    }

    glslang_program_SPIRV_generate(program, stage);

    bin.size = glslang_program_SPIRV_get_size(program);
    bin.words = malloc(bin.size * sizeof(uint32_t));
    glslang_program_SPIRV_get(program, bin.words);

    glslang_program_delete(program);
    glslang_shader_delete(shader);

    return bin;
}