From 72917ccdb357ff1fa08bca2075b3692734d7f76e Mon Sep 17 00:00:00 2001
From: Robin Voetter <robin@voetter.nl>
Date: Sat, 4 Jul 2020 04:18:56 +0200
Subject: [PATCH] Shader compilation utility

---
 examples/shaders/test.frag             |  7 ++++
 generator/build-integration.zig        | 54 ++++++++++++++++++++++++++
 generator/vulkan/build-integration.zig | 14 +++----
 3 files changed, 68 insertions(+), 7 deletions(-)
 create mode 100644 examples/shaders/test.frag
 create mode 100644 generator/build-integration.zig

diff --git a/examples/shaders/test.frag b/examples/shaders/test.frag
new file mode 100644
index 0000000..40e75e9
--- /dev/null
+++ b/examples/shaders/test.frag
@@ -0,0 +1,7 @@
+#version 450
+
+layout(location = 0) out vec4 f_color;
+
+void main() {
+    f_color = vec4(1.0, 0.0, 0.0, 1.0);
+}
diff --git a/generator/build-integration.zig b/generator/build-integration.zig
new file mode 100644
index 0000000..d0c1a55
--- /dev/null
+++ b/generator/build-integration.zig
@@ -0,0 +1,54 @@
+const std = @import("std");
+const path = std.fs.path;
+const Builder = std.build.Builder;
+const Step = std.build.Step;
+
+pub const ShaderCompileStep = struct {
+    const Shader = struct {
+        source_path: []const u8,
+        full_out_path: []const u8,
+    };
+
+    step: Step,
+    builder: *Builder,
+    glslc_path: []const u8,
+    shaders: std.ArrayList(Shader),
+
+    pub fn init(builder: *Builder, glslc_path: []const u8) *ShaderCompileStep {
+        const self = builder.allocator.create(ShaderCompileStep) catch unreachable;
+        self.* = .{
+            .step = Step.init(.Custom, "shader-compile", builder.allocator, make),
+            .builder = builder,
+            .glslc_path = glslc_path,
+            .shaders = std.ArrayList(Shader).init(builder.allocator),
+        };
+        return self;
+    }
+
+    pub fn add(self: *ShaderCompileStep, src: []const u8) []const u8 {
+        const full_out_path = path.join(self.builder.allocator, &[_][]const u8{
+            self.builder.build_root,
+            self.builder.cache_root,
+            "shaders",
+            src,
+        }) catch unreachable;
+        self.shaders.append(.{.source_path = src, .full_out_path = full_out_path}) catch unreachable;
+        return full_out_path;
+    }
+
+    fn make(step: *Step) !void {
+        const self = @fieldParentPtr(ShaderCompileStep, "step", step);
+        const cwd = std.fs.cwd();
+
+        for (self.shaders.items) |shader| {
+            const dir = path.dirname(shader.full_out_path).?;
+            try cwd.makePath(dir);
+            try self.builder.spawnChild(&[_][]const u8{
+                self.glslc_path,
+                shader.source_path,
+                "-o",
+                shader.full_out_path,
+            });
+        }
+    }
+};
diff --git a/generator/vulkan/build-integration.zig b/generator/vulkan/build-integration.zig
index ce3c36a..e5408fc 100644
--- a/generator/vulkan/build-integration.zig
+++ b/generator/vulkan/build-integration.zig
@@ -10,16 +10,17 @@ pub const GenerateStep = struct {
     spec_path: []const u8,
     full_out_path: []const u8,
 
-    // relative_out_path is relative to builder.cache_root
-    pub fn init(builder: *Builder, spec_path: []const u8, relative_out_path: []const u8) *GenerateStep {
+    // out_path is relative to builder.cache_root
+    pub fn init(builder: *Builder, spec_path: []const u8, out_path: []const u8) *GenerateStep {
         const self = builder.allocator.create(GenerateStep) catch unreachable;
         self.* = .{
             .step = Step.init(.Custom, "vulkan-generate", builder.allocator, make),
             .builder = builder,
             .spec_path = spec_path,
             .full_out_path = path.join(builder.allocator, &[_][]const u8{
+                self.builder.build_root,
                 builder.cache_root,
-                relative_out_path,
+                out_path,
             }) catch unreachable,
         };
         return self;
@@ -28,16 +29,15 @@ pub const GenerateStep = struct {
     fn make(step: *Step) !void {
         const self = @fieldParentPtr(GenerateStep, "step", step);
         const cwd = std.fs.cwd();
-
         var out_buffer = std.ArrayList(u8).init(self.builder.allocator);
-        const spec = try std.fs.cwd().readFileAlloc(self.builder.allocator, self.spec_path, std.math.maxInt(usize));
+        const spec = try cwd.readFileAlloc(self.builder.allocator, self.spec_path, std.math.maxInt(usize));
         try generate(self.builder.allocator, spec, out_buffer.writer());
 
         const tree = try std.zig.parse(self.builder.allocator, out_buffer.items);
 
         const dir = path.dirname(self.full_out_path).?;
-        try std.fs.cwd().makePath(dir);
-        const output_file = std.fs.cwd().createFile(self.full_out_path, .{}) catch unreachable;
+        try cwd.makePath(dir);
+        const output_file = cwd.createFile(self.full_out_path, .{}) catch unreachable;
         _ = try std.zig.render(self.builder.allocator, output_file.outStream(), tree);
     }
 };