From 34ca91f6f77f0d80f952c6b8a037e5bc929b33f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Przemys=C5=82aw=20Gasi=C7=B9ski?= <przemek@gasinski.eu>
Date: Fri, 28 Jun 2024 22:35:32 +0200
Subject: [PATCH] Start implementing the graphics pipeline

---
 build.zig               | 10 ++++++++++
 src/shaders/shader.frag | 11 +++++++++++
 src/shaders/shader.vert | 23 +++++++++++++++++++++++
 src/vulkan_renderer.zig | 39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 src/shaders/shader.frag
 create mode 100644 src/shaders/shader.vert

diff --git a/build.zig b/build.zig
index f51b0fc..7796f98 100644
--- a/build.zig
+++ b/build.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const sdl = @import("sdl");
+const vkgen = @import("vulkan_zig");
 
 // Although this function looks imperative, note that its job is to
 // declaratively construct a build graph that will be executed by an external
@@ -29,6 +30,15 @@ pub fn build(b: *std.Build) void {
     const vkzig_bindings = vkzig_dep.module("vulkan-zig");
     exe.root_module.addImport("vulkan", vkzig_bindings);
 
+    const shader_comp = vkgen.ShaderCompileStep.create(
+        b,
+        &[_][]const u8{ "glslc", "--target-env=vulkan1.3" },
+        "-o",
+    );
+    shader_comp.add("shader_frag", "src/shaders/shader.frag", .{});
+    shader_comp.add("shader_vert", "src/shaders/shader.vert", .{});
+    exe.root_module.addImport("shaders", shader_comp.getModule());
+
     const sdl_sdk = sdl.init(b, null);
     sdl_sdk.link(exe, .dynamic);
 
diff --git a/src/shaders/shader.frag b/src/shaders/shader.frag
new file mode 100644
index 0000000..edeac14
--- /dev/null
+++ b/src/shaders/shader.frag
@@ -0,0 +1,11 @@
+#version 450
+
+// Interpolated colour from vertex (location must match)
+layout(location = 0) in vec3 fragColour;
+
+// Final output output (must also have location)
+layout(location = 0) out vec4 outColour;
+
+void main() {
+    outColour = vec4(fragColour, 1.0);
+}
diff --git a/src/shaders/shader.vert b/src/shaders/shader.vert
new file mode 100644
index 0000000..7a51229
--- /dev/null
+++ b/src/shaders/shader.vert
@@ -0,0 +1,23 @@
+#version 450
+
+// Output colour for vertex (location is required)
+layout(location = 0) out vec3 fragColour;
+
+// Triangle vertex positions
+vec3 positions[3] = vec3[](
+        vec3(0.0, -0.4, 0.0),
+        vec3(0.4, 0.4, 0.0),
+        vec3(-0.4, 0.4, 0.0)
+    );
+
+// Triangle vertex colours
+vec3 colours[3] = vec3[](
+        vec3(1.0, 0.0, 0.0),
+        vec3(0.0, 1.0, 0.0),
+        vec3(0.0, 0.0, 1.0)
+    );
+
+void main() {
+    gl_Position = vec4(positions[gl_VertexIndex], 1.0);
+    fragColour = colours[gl_VertexIndex];
+}
diff --git a/src/vulkan_renderer.zig b/src/vulkan_renderer.zig
index 72fff8a..5263ba8 100644
--- a/src/vulkan_renderer.zig
+++ b/src/vulkan_renderer.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 const sdl = @import("sdl2");
 const vk = @import("vulkan");
 const builtin = @import("builtin");
+const shaders = @import("shaders");
 
 const Utilities = @import("utilities.zig");
 const QueueFamilyIndices = Utilities.QueueFamilyIndices;
@@ -71,6 +72,7 @@ pub const VulkanRenderer = struct {
         try self.getPhysicalDevice();
         try self.createLogicalDevice();
         try self.createSwapchain();
+        try self.createGraphicsPipeline();
 
         return self;
     }
@@ -248,6 +250,43 @@ pub const VulkanRenderer = struct {
         }
     }
 
+    fn createGraphicsPipeline(self: *Self) !void {
+        // Create shader modules
+        const vert = try self.device.createShaderModule(&.{
+            .code_size = shaders.shader_vert.len,
+            .p_code = @ptrCast(&shaders.shader_vert),
+        }, null);
+        defer self.device.destroyShaderModule(vert, null);
+
+        const frag = try self.device.createShaderModule(&.{
+            .code_size = shaders.shader_frag.len,
+            .p_code = @ptrCast(&shaders.shader_frag),
+        }, null);
+        defer self.device.destroyShaderModule(frag, null);
+
+        // -- Shader stage creation information
+
+        // Vertex stage creation information
+        const vertex_shader_create_info: vk.PipelineShaderStageCreateInfo = .{
+            .stage = .{ .vertex_bit = true },
+            .module = vert,
+            .p_name = "main",
+        };
+
+        // Fragment stage creation information
+        const fragment_shader_create_info: vk.PipelineShaderStageCreateInfo = .{
+            .stage = .{ .fragment_bit = true },
+            .module = frag,
+            .p_name = "main",
+        };
+
+        const shader_create_infos = [_]vk.PipelineShaderStageCreateInfo{
+            vertex_shader_create_info,
+            fragment_shader_create_info,
+        };
+        _ = shader_create_infos;
+    }
+
     fn getPhysicalDevice(self: *Self) !void {
         var pdev_count: u32 = 0;
         _ = try self.instance.enumeratePhysicalDevices(&pdev_count, null);