From 5b1d5fc0325dc5e20ccb7b1ce445721762256848 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Yaroslav=20de=20la=20Pe=C3=B1a=20Smirnov?=
 <yps@yaroslavps.com>
Date: Wed, 18 Sep 2024 00:02:33 +0300
Subject: opengl: triangle

OpenGL hello world triangle on Wayland.
---
 src/egl.zig | 186 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 186 insertions(+)
 create mode 100644 src/egl.zig

(limited to 'src/egl.zig')

diff --git a/src/egl.zig b/src/egl.zig
new file mode 100644
index 0000000..ad5be7c
--- /dev/null
+++ b/src/egl.zig
@@ -0,0 +1,186 @@
+const c = @cImport({
+    @cInclude("EGL/egl.h");
+    @cInclude("GL/gl.h");
+});
+
+pub const Error = error{
+    Unknown,
+    NoDisplay,
+    NotInitialized,
+    BadAccess,
+    BadAlloc,
+    BadAttribute,
+    BadContext,
+    BadConfig,
+    BadCurrentSurface,
+    BadDisplay,
+    BadMatch,
+    BadNativePixmap,
+    BadNativeWindow,
+    BadParameter,
+    BadSurface,
+    ContextLost,
+};
+
+extern fn eglGetError() i32;
+fn getError() Error!void {
+    return switch (eglGetError()) {
+        c.EGL_NOT_INITIALIZED => Error.NotInitialized,
+        c.EGL_BAD_ACCESS => Error.BadDisplay,
+        c.EGL_BAD_ATTRIBUTE => Error.BadAttribute,
+        c.EGL_BAD_CONFIG => Error.BadConfig,
+        c.EGL_BAD_CONTEXT => Error.BadContext,
+        c.EGL_BAD_CURRENT_SURFACE => Error.BadCurrentSurface,
+        c.EGL_BAD_DISPLAY => Error.BadDisplay,
+        c.EGL_BAD_MATCH => Error.BadMatch,
+        c.EGL_BAD_NATIVE_PIXMAP => Error.BadNativePixmap,
+        c.EGL_BAD_NATIVE_WINDOW => Error.BadNativeWindow,
+        c.EGL_BAD_PARAMETER => Error.BadParameter,
+        c.EGL_BAD_SURFACE => Error.BadSurface,
+        c.EGL_CONTEXT_LOST => Error.ContextLost,
+        else => Error.Unknown,
+    };
+}
+
+pub const Api = enum(u32) {
+    opengl = c.EGL_OPENGL_API,
+    opengl_es = c.EGL_OPENGL_ES_API,
+};
+
+extern fn eglBindAPI(api: Api) bool;
+pub fn bindApi(api: Api) Error!void {
+    if (!eglBindAPI(api)) try getError();
+}
+
+pub const AttributeType = enum(i32) {
+    none = c.EGL_NONE,
+    alpha_size = c.EGL_ALPHA_SIZE,
+    red_size = c.EGL_RED_SIZE,
+    green_size = c.EGL_GREEN_SIZE,
+    blue_size = c.EGL_BLUE_SIZE,
+};
+
+pub const Attribute = packed struct {
+    type: AttributeType,
+    value: i32,
+};
+
+pub const Config = opaque {};
+
+pub const Surface = opaque {};
+
+pub const Context = opaque {};
+
+pub const Display = opaque {
+    extern fn eglGetDisplay(native_display: *anyopaque) ?*Display;
+    pub fn get(native_display: *anyopaque) Error!*Display {
+        return eglGetDisplay(
+            native_display,
+        ) orelse Error.NoDisplay;
+    }
+
+    extern fn eglInitialize(display: *Display, major: ?*i32, minor: ?*i32) bool;
+    pub fn initialize(display: *Display, major: ?*i32, minor: ?*i32) Error!void {
+        if (!eglInitialize(display, major, minor)) try getError();
+    }
+
+    extern fn eglChooseConfig(
+        display: *Display,
+        attributes: [*c]Attribute,
+        configs: [*c]*Config,
+        configs_len: i32,
+        config_cnt: *i32,
+    ) bool;
+    /// Returns the number of configs that were put in @configs.
+    pub fn chooseConfig(
+        display: *Display,
+        attributes: []Attribute,
+        configs: []*Config,
+    ) Error!i32 {
+        var config_cnt: i32 = 0;
+        if (!eglChooseConfig(
+            display,
+            attributes.ptr,
+            configs.ptr,
+            @intCast(configs.len),
+            &config_cnt,
+        )) {
+            try getError();
+        }
+        return config_cnt;
+    }
+
+    extern fn eglCreateContext(
+        display: *Display,
+        config: *Config,
+        share_ctx: ?*Context,
+        attributes: [*c]Attribute,
+    ) ?*Context;
+    pub fn createContext(
+        display: *Display,
+        config: *Config,
+        share_ctx: ?*Context,
+        attributes: ?[]Attribute,
+    ) Error!*Context {
+        var attrs: [*c]Attribute = null;
+        if (attributes) |_attrs| attrs = _attrs.ptr;
+        return eglCreateContext(display, config, share_ctx, attrs) orelse {
+            try getError();
+            unreachable;
+        };
+    }
+
+    extern fn eglCreateWindowSurface(
+        display: *Display,
+        config: *Config,
+        native_window: *anyopaque,
+        attributes: [*c]Attribute,
+    ) ?*Surface;
+    pub fn createWindowSurface(
+        display: *Display,
+        config: *Config,
+        native_window: *anyopaque,
+        attributes: ?[]Attribute,
+    ) Error!*Surface {
+        var attrs: [*c]Attribute = null;
+        if (attributes) |_attrs| attrs = _attrs.ptr;
+        return eglCreateWindowSurface(display, config, native_window, attrs) orelse {
+            try getError();
+            unreachable;
+        };
+    }
+
+    extern fn eglMakeCurrent(
+        display: *Display,
+        draw: *Surface,
+        read: *Surface,
+        ctx: *Context,
+    ) bool;
+    pub fn makeCurrent(
+        display: *Display,
+        draw: *Surface,
+        read: *Surface,
+        ctx: *Context,
+    ) Error!void {
+        if (!eglMakeCurrent(display, draw, read, ctx)) try getError();
+    }
+
+    extern fn eglQueryString(display: *Display, name: i32) [*:0]const u8;
+    pub const queryString = eglQueryString;
+
+    extern fn eglSwapBuffers(display: *Display, surface: *Surface) bool;
+    pub fn swapBuffers(display: *Display, surface: *Surface) Error!void {
+        if (!eglSwapBuffers(display, surface)) try getError();
+    }
+
+    extern fn eglSwapInterval(display: *Display, interval: i32) bool;
+    pub fn swapInterval(display: *Display, interval: i32) Error!void {
+        if (!eglSwapInterval(display, interval)) try getError();
+    }
+
+    extern fn eglTerminate(display: *Display) bool;
+    pub fn terminate(display: *Display) void {
+        // Do I really care if destruction fails?
+        _ = eglTerminate(display);
+    }
+};
-- 
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