From 3e1aea0243f54e0b68baa3b19ac19f3d965484e0 Mon Sep 17 00:00:00 2001
From: omniscient <17525998+omnisci3nce@users.noreply.github.com>
Date: Thu, 17 Oct 2024 16:49:11 +1100
Subject: start on metal backend

---
 src/backend_mtl.m | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

(limited to 'src/backend_mtl.m')

diff --git a/src/backend_mtl.m b/src/backend_mtl.m
index 9a99e14..b3cd224 100644
--- a/src/backend_mtl.m
+++ b/src/backend_mtl.m
@@ -3,20 +3,66 @@
 #ifdef GPU_METAL
 #include <celeritas.h>
 
+#define MTL_DEBUG_LAYER 1
+
 // Obj-C imports
 #import <Foundation/Foundation.h>
 #import <Metal/Metal.h>
 #import <MetalKit/MetalKit.h>
 #import <QuartzCore/CAMetalLayer.h>
 
+#define GLFW_INCLUDE_NONE
+#import <GLFW/glfw3.h>
+#define GLFW_EXPOSE_NATIVE_COCOA
+#import <GLFW/glfw3native.h>
+
 // --- RAL types
-struct gpu_device {
-  id<MTLDevice> id;
-};
 
 struct gpu_swapchain {
   int width, height;
   CAMetalLayer* swapchain;
 };
 
+typedef struct metal_context {
+  GLFWwindow* window;
+  NSWindow* metal_window;
+
+  id<MTLDevice> device;
+  id<CAMetalDrawable> surface;
+  gpu_swapchain default_swapchain;
+
+  id<MTLCommandQueue> command_queue;
+} metal_context;
+
+static metal_context ctx;
+
+void ral_backend_init(const char* window_name, struct GLFWwindow* window) {
+  printf("loading Metal backend\n");
+
+  printf("gpu device creation\n");
+  const id<MTLDevice> gpu = MTLCreateSystemDefaultDevice();
+  ctx.device = gpu;
+
+  printf("window init\n");
+  glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
+  glfwMakeContextCurrent(window);
+  NSWindow* nswindow = glfwGetCocoaWindow(window);
+  ctx.metal_window = nswindow;
+
+  // effectively the "framebuffer"
+  CAMetalLayer* metal_layer = [CAMetalLayer layer];
+  metal_layer.device = gpu;
+  metal_layer.pixelFormat = MTLPixelFormatBGRA8Unorm;
+  ctx.metal_window.contentView.layer = metal_layer;
+  ctx.metal_window.contentView.wantsLayer = true;
+
+  printf("command queue creation\n");
+  const id<MTLCommandQueue> queue = [ctx.device newCommandQueue];
+  ctx.command_queue = queue;
+}
+
+void ral_backend_shutdown() {
+  // no-op
+}
+
 #endif
\ No newline at end of file
-- 
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