From b051d0c406be7e0d72d41043f679c8fb778a8331 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Sun, 1 Jan 2023 02:17:33 -0600
Subject: [PATCH 1/3] feat: add sdl2-opengl3 backend impl

---
 src/backend_sdl2_opengl3.zig | 42 ++++++++++++++++++++++++++++++++++++
 src/main.zig                 |  2 ++
 2 files changed, 44 insertions(+)
 create mode 100644 src/backend_sdl2_opengl3.zig

diff --git a/src/backend_sdl2_opengl3.zig b/src/backend_sdl2_opengl3.zig
new file mode 100644
index 0000000..7eeb081
--- /dev/null
+++ b/src/backend_sdl2_opengl3.zig
@@ -0,0 +1,42 @@
+const zgui = @import("gui.zig");
+
+const SDL_GL_Context = *anyopaque;
+
+pub fn init(window: *anyopaque, context: SDL_GL_Context, glsl_version: []const u8) void {
+    if (!ImGui_ImplSDL2_InitForOpenGL(window, context)) unreachable;
+    if (!ImGui_ImplOpenGL3_Init(glsl_version.ptr)) unreachable;
+}
+
+pub fn deinit() void {
+    ImGui_ImplOpenGL3_Shutdown();
+    ImGui_ImplSDL2_Shutdown();
+}
+
+pub fn newFrame(width: f32, height: f32) void {
+    ImGui_ImplOpenGL3_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+
+    zgui.io.setDisplaySize(width, height);
+    zgui.io.setDisplayFramebufferScale(1.0, 1.0);
+
+    zgui.newFrame();
+}
+
+pub fn draw() void {
+    zgui.render();
+    ImGui_ImplOpenGL3_RenderDrawData(zgui.getDrawData());
+}
+
+pub fn processEvent(event: *anyopaque) bool {
+    return ImGui_ImplSDL2_ProcessEvent(event);
+}
+
+extern fn ImGui_ImplSDL2_InitForOpenGL(window: *anyopaque, sdl_gl_context: SDL_GL_Context) bool;
+extern fn ImGui_ImplSDL2_Shutdown() void;
+extern fn ImGui_ImplSDL2_NewFrame() void;
+extern fn ImGui_ImplSDL2_ProcessEvent(event: *anyopaque) bool;
+
+extern fn ImGui_ImplOpenGL3_Init(glsl_version: [*]const u8) bool;
+extern fn ImGui_ImplOpenGL3_Shutdown() void;
+extern fn ImGui_ImplOpenGL3_NewFrame() void;
+extern fn ImGui_ImplOpenGL3_RenderDrawData(draw_data: *anyopaque) void;
diff --git a/src/main.zig b/src/main.zig
index 3c85326..9c4cc9d 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -10,6 +10,8 @@ pub usingnamespace @import("gui.zig");
 pub const plot = @import("plot.zig");
 pub const backend = switch (@import("zgui_options").backend) {
     .glfw_wgpu => @import("backend_glfw_wgpu.zig"),
+    .glfw_opengl3 => {}, // See glfw-opengl3-backend branch
+    .sdl2_opengl3 => @import("backend_sdl2_opengl3.zig"),
     .win32_dx12 => .{}, // TODO:
     .no_backend => .{},
 };

From 78922b64eac856e5f28c9fb27bf7b0e1c96d8f1b Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Sun, 1 Jan 2023 12:54:18 -0600
Subject: [PATCH 2/3] fix: vcpkg stores SDL.h under SDL2 folder

macOS and Linux seem to not, so in order to get CI working again I
should make use of the preprocessor.

FIXME: I think this makes vcpkg a **hard** requirement which perhaps
isn't ideal if I want ZBA to be as easy to build as possible. I should
try ensuring that building w/out vcpkg works as well
---
 libs/imgui/backends/imgui_impl_sdl.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/libs/imgui/backends/imgui_impl_sdl.cpp b/libs/imgui/backends/imgui_impl_sdl.cpp
index fc26bf3..d63c6e4 100644
--- a/libs/imgui/backends/imgui_impl_sdl.cpp
+++ b/libs/imgui/backends/imgui_impl_sdl.cpp
@@ -67,8 +67,14 @@
 #include "imgui_impl_sdl.h"
 
 // SDL
-#include <SDL.h>
-#include <SDL_syswm.h>
+#if defined(__WIN32__)
+    #include <SDL2/SDL.h>
+    #include <SDL2/SDL_syswm.h>
+#else
+    #include <SDL.h>
+    #include <SDL_syswm.h>
+#endif
+
 #if defined(__APPLE__)
 #include <TargetConditionals.h>
 #endif

From 55efe08bdfef961e9081f3cf63ba9c2c163fa8c4 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Fri, 10 Mar 2023 22:04:35 -0600
Subject: [PATCH 3/3] chore: explicitly link SDL2

TODO: What happens on Windows? macOS?
---
 build.zig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/build.zig b/build.zig
index 50f3e3c..3c1e15a 100644
--- a/build.zig
+++ b/build.zig
@@ -107,6 +107,7 @@ pub fn package(
         .sdl2_opengl3 => {
             zgui_c_cpp.addCSourceFile(thisDir() ++ "/libs/imgui/backends/imgui_impl_sdl.cpp", cflags);
             zgui_c_cpp.addCSourceFile(thisDir() ++ "/libs/imgui/backends/imgui_impl_opengl3.cpp", cflags);
+            zgui_c_cpp.linkSystemLibrary("SDL2");
         },
         .no_backend => {},
     }