impeller/tools/shaders_mtl.gni

# Copyright 2013 The Flutter Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//flutter/impeller/tools/args.gni")
import("//flutter/impeller/tools/compiler.gni")
import("//flutter/impeller/tools/embed_blob.gni")
import("//flutter/impeller/tools/metal_library.gni")

template("impeller_shaders_metal") {
  assert(defined(invoker.shaders), "Impeller shaders must be specified.")
  assert(defined(invoker.name), "Name of the shader library must be specified.")

  metal_version = "1.2"
  if (defined(invoker.metal_version)) {
    metal_version = invoker.metal_version
  }

  use_half_textures = false
  if (defined(invoker.use_half_textures) && invoker.use_half_textures) {
    use_half_textures = invoker.use_half_textures
  }

  shaders_base_name = string_join("",
                                  [
                                    invoker.name,
                                    "_shaders",
                                  ])
  impellerc_mtl = "impellerc_$target_name"
  impellerc(impellerc_mtl) {
    shaders = invoker.shaders
    metal_version = metal_version
    sl_file_extension = "metal"
    use_half_textures = use_half_textures
    shader_target_flags = []
    defines = [ "IMPELLER_TARGET_METAL" ]
    if (is_ios) {
      shader_target_flags += [ "--metal-ios" ]
      defines += [ "IMPELLER_TARGET_METAL_IOS" ]
    } else if (is_mac) {
      shader_target_flags = [ "--metal-desktop" ]
      defines += [ "IMPELLER_TARGET_METAL_DESKTOP" ]
    } else {
      assert(false, "Metal not supported on this platform.")
    }
  }

  mtl_lib = "genlib_$target_name"
  metal_library(mtl_lib) {
    name = invoker.name
    metal_version = metal_version
    sources =
        filter_include(get_target_outputs(":$impellerc_mtl"), [ "*.metal" ])
    deps = [ ":$impellerc_mtl" ]
  }

  reflect_mtl = "reflect_$target_name"
  impellerc_reflect(reflect_mtl) {
    impellerc_invocation = ":$impellerc_mtl"
  }

  embed_mtl_lib = "embed_$target_name"
  embed_blob(embed_mtl_lib) {
    metal_library_files = get_target_outputs(":$mtl_lib")
    symbol_name = shaders_base_name
    blob = metal_library_files[0]
    hdr = "$target_gen_dir/mtl/$shaders_base_name.h"
    cc = "$target_gen_dir/mtl/$shaders_base_name.cc"
    deps = [ ":$mtl_lib" ]
  }

  group(target_name) {
    public_deps = [
      ":$embed_mtl_lib",
      ":$reflect_mtl",
    ]
  }
}