Initial commit.

renderer_backend_opengl_windows.odin

@@ -0,0 +1,93 @@
+package renderer
+
+import "core:fmt"
+import gl "vendor:OpenGL"
+import win "core:sys/windows"
+
+
+when RENDER_BACKEND_OPENGL {
+    Backend_OpenGL_Windows :: struct {
+        hwnd: win.HWND,
+        hdc: win.HDC,
+        gl_context: win.HGLRC,
+    }
+
+    backend: Backend_OpenGL_Windows
+    
+    opengl_init :: proc(renderer: ^Renderer) -> bool {
+        renderer.backend = &backend
+
+        backend.hwnd = win.HWND(renderer.surface_ptr)
+        backend.hdc = win.GetDC(backend.hwnd)
+
+        pfd := win.PIXELFORMATDESCRIPTOR {
+            nSize = size_of(win.PIXELFORMATDESCRIPTOR),
+            nVersion = 1,
+            dwFlags = win.PFD_DRAW_TO_WINDOW | win.PFD_SUPPORT_OPENGL | win.PFD_DOUBLEBUFFER,
+            iPixelType = win.PFD_TYPE_RGBA,
+            cColorBits = 32,
+            cDepthBits = 24,
+            cStencilBits = 8,
+            iLayerType = win.PFD_MAIN_PLANE,
+        }
+
+        format_index := win.ChoosePixelFormat(backend.hdc, &pfd)
+        assert(format_index != 0, "ChoosePixelFormat failed")
+
+        set_pixel_format_ok := win.SetPixelFormat(backend.hdc, format_index, &pfd)
+        assert(set_pixel_format_ok == win.TRUE, "SetPixelFormat failed")
+
+        backend.gl_context = win.wglCreateContext(backend.hdc)
+        assert(backend.gl_context != nil, "Failed to create OpenGL context")
+
+        win.wglMakeCurrent(backend.hdc, backend.gl_context)
+        // fmt.printfln("GL Context: %v", backend.gl_context)
+
+        gl.load_up_to(3, 3, proc(p: rawptr, name: cstring) {
+            addr := win.wglGetProcAddress(name)
+            if addr == nil {
+                dll := win.LoadLibraryW(win.utf8_to_wstring("opengl32.dll"))
+                addr = win.GetProcAddress(dll, name)
+            }
+            (^rawptr)(p)^ = addr
+        })
+
+
+        opengl_swap_buffers(renderer)
+
+        return true
+    }
+
+    opengl_viewport_changed :: proc(renderer: ^Renderer) {
+        gl.Clear(gl.COLOR_BUFFER_BIT)
+
+        gl.Viewport(
+            i32(renderer.viewport.x),
+            i32(renderer.viewport.y),
+            i32(renderer.viewport.width),
+            i32(renderer.viewport.height)
+        )
+    }
+
+    opengl_set_clear_color :: proc(renderer: ^Renderer, color: [3]u8) {
+        gl.ClearColor(
+            f32(color.r) / f32(max(u8)),
+            f32(color.g) / f32(max(u8)),
+            f32(color.b) / f32(max(u8)),
+            1.0
+        )
+    }
+
+    opengl_swap_buffers :: proc(renderer: ^Renderer) {
+        gl.Clear(gl.COLOR_BUFFER_BIT)
+        win.SwapBuffers(backend.hdc)
+    }
+
+    opengl_destroy :: proc(renderer: ^Renderer) {
+        win.wglMakeCurrent(nil, nil)
+        win.wglDeleteContext(backend.gl_context)
+        win.ReleaseDC(backend.hwnd, backend.hdc)
+
+        backend = {}
+    }
+}