gpu-dawn: use cross-platform process.getEnvVarOwned

Helps #86 Signed-off-by: Stephen Gutekanst <[email protected]>
hexops · Feb 21, 2022 · e451e4a · e451e4a
1 parent 918bc61
commit e451e4a
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Showing 2 changed files with 14 additions and 5 deletions.
diff --git a/gpu-dawn/src/dawn/hello_triangle.zig b/gpu-dawn/src/dawn/hello_triangle.zig
@@ -15,7 +15,7 @@ pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     var allocator = gpa.allocator();
 
-    const setup = try sample_utils.setup();
+    const setup = try sample_utils.setup(allocator);
     const queue = c.wgpuDeviceGetQueue(setup.device);
 
     var descriptor = std.mem.zeroes(c.WGPUSwapChainDescriptor);

diff --git a/gpu-dawn/src/dawn/sample_utils.zig b/gpu-dawn/src/dawn/sample_utils.zig
@@ -51,8 +51,17 @@ const Setup = struct {
     window: glfw.Window,
 };
 
-fn detectBackendType() c.WGPUBackendType {
-    if (std.os.getenv("WGPU_BACKEND")) |backend| {
+fn getEnvVarOwned(allocator: std.mem.Allocator, key: []const u8) error{ OutOfMemory, InvalidUtf8 }!?[]u8 {
+    return std.process.getEnvVarOwned(allocator, key) catch |err| switch (err) {
+        error.EnvironmentVariableNotFound => @as(?[]u8, null),
+        else => |e| e,
+    };
+}
+
+fn detectBackendType(allocator: std.mem.Allocator) !c.WGPUBackendType {
+    const WGPU_BACKEND = try getEnvVarOwned(allocator, "WGPU_BACKEND");
+    if (WGPU_BACKEND) |backend| {
+        defer allocator.free(backend);
         if (std.ascii.eqlIgnoreCase(backend, "opengl")) return c.WGPUBackendType_OpenGL;
         if (std.ascii.eqlIgnoreCase(backend, "opengles")) return c.WGPUBackendType_OpenGLES;
         if (std.ascii.eqlIgnoreCase(backend, "d3d11")) return c.WGPUBackendType_D3D11;
@@ -82,8 +91,8 @@ fn backendTypeString(t: c.WGPUBackendType) []const u8 {
     };
 }
 
-pub fn setup() !Setup {
-    const backend_type = detectBackendType();
+pub fn setup(allocator: std.mem.Allocator) !Setup {
+    const backend_type = try detectBackendType(allocator);
     const cmd_buf_type = CmdBufType.none;
 
     try glfw.init(.{});