make opengl loader context-aware

src/Window.zig

@@ -242,12 +242,12 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
 
     // Culling, probably not necessary. We have to change the winding
     // order since our 0,0 is top-left.
-    gl.c.glEnable(gl.c.GL_CULL_FACE);
-    gl.c.glFrontFace(gl.c.GL_CW);
+    try gl.enable(gl.c.GL_CULL_FACE);
+    try gl.frontFace(gl.c.GL_CW);
 
     // Blending for text
-    gl.c.glEnable(gl.c.GL_BLEND);
-    gl.c.glBlendFunc(gl.c.GL_SRC_ALPHA, gl.c.GL_ONE_MINUS_SRC_ALPHA);
+    try gl.enable(gl.c.GL_BLEND);
+    try gl.blendFunc(gl.c.GL_SRC_ALPHA, gl.c.GL_ONE_MINUS_SRC_ALPHA);
 
     // The font size we desire along with the DPI determiend for the window
     const font_size: font.face.DesiredSize = .{

src/opengl/Buffer.zig

@@ -3,6 +3,7 @@ const Buffer = @This();
 const std = @import("std");
 const c = @import("c.zig");
 const errors = @import("errors.zig");
+const glad = @import("glad.zig");
 
 id: c.GLuint,
 
@@ -41,7 +42,7 @@ pub const Binding = struct {
         usage: Usage,
     ) !void {
         const info = dataInfo(&data);
-        c.glBufferData(@enumToInt(b.target), info.size, info.ptr, @enumToInt(usage));
+        glad.context.BufferData.?(@enumToInt(b.target), info.size, info.ptr, @enumToInt(usage));
         try errors.getError();
     }
 
@@ -53,7 +54,7 @@ pub const Binding = struct {
         data: anytype,
     ) !void {
         const info = dataInfo(data);
-        c.glBufferSubData(@enumToInt(b.target), @intCast(c_long, offset), info.size, info.ptr);
+        glad.context.BufferSubData.?(@enumToInt(b.target), @intCast(c_long, offset), info.size, info.ptr);
         try errors.getError();
     }
 
@@ -65,7 +66,7 @@ pub const Binding = struct {
         comptime T: type,
         usage: Usage,
     ) !void {
-        c.glBufferData(@enumToInt(b.target), @sizeOf(T), null, @enumToInt(usage));
+        glad.context.BufferData.?(@enumToInt(b.target), @sizeOf(T), null, @enumToInt(usage));
         try errors.getError();
     }
 
@@ -75,7 +76,7 @@ pub const Binding = struct {
         size: usize,
         usage: Usage,
     ) !void {
-        c.glBufferData(@enumToInt(b.target), @intCast(c_long, size), null, @enumToInt(usage));
+        glad.context.BufferData.?(@enumToInt(b.target), @intCast(c_long, size), null, @enumToInt(usage));
         try errors.getError();
     }
 
@@ -106,7 +107,7 @@ pub const Binding = struct {
     }
 
     pub inline fn enableAttribArray(_: Binding, idx: c.GLuint) !void {
-        c.glEnableVertexAttribArray(idx);
+        glad.context.EnableVertexAttribArray.?(idx);
     }
 
     /// Shorthand for vertexAttribPointer that is specialized towards the
@@ -153,7 +154,7 @@ pub const Binding = struct {
 
     /// VertexAttribDivisor
     pub fn attributeDivisor(_: Binding, idx: c.GLuint, divisor: c.GLuint) !void {
-        c.glVertexAttribDivisor(idx, divisor);
+        glad.context.VertexAttribDivisor.?(idx, divisor);
         try errors.getError();
     }
 
@@ -172,7 +173,7 @@ pub const Binding = struct {
         else
             null;
 
-        c.glVertexAttribPointer(idx, size, typ, normalized_c, stride, offsetPtr);
+        glad.context.VertexAttribPointer.?(idx, size, typ, normalized_c, stride, offsetPtr);
         try errors.getError();
     }
 
@@ -189,12 +190,12 @@ pub const Binding = struct {
         else
             null;
 
-        c.glVertexAttribIPointer(idx, size, typ, stride, offsetPtr);
+        glad.context.VertexAttribIPointer.?(idx, size, typ, stride, offsetPtr);
         try errors.getError();
     }
 
     pub inline fn unbind(b: *Binding) void {
-        c.glBindBuffer(@enumToInt(b.target), 0);
+        glad.context.BindBuffer.?(@enumToInt(b.target), 0);
         b.* = undefined;
     }
 };
@@ -202,16 +203,16 @@ pub const Binding = struct {
 /// Create a single buffer.
 pub inline fn create() !Buffer {
     var vbo: c.GLuint = undefined;
-    c.glGenBuffers(1, &vbo);
+    glad.context.GenBuffers.?(1, &vbo);
     return Buffer{ .id = vbo };
 }
 
 /// glBindBuffer
 pub inline fn bind(v: Buffer, target: Target) !Binding {
-    c.glBindBuffer(@enumToInt(target), v.id);
+    glad.context.BindBuffer.?(@enumToInt(target), v.id);
     return Binding{ .target = target };
 }
 
 pub inline fn destroy(v: Buffer) void {
-    c.glDeleteBuffers(1, &v.id);
+    glad.context.DeleteBuffers.?(1, &v.id);
 }

src/opengl/Program.zig

@@ -7,17 +7,18 @@ const log = std.log.scoped(.opengl);
 const c = @import("c.zig");
 const Shader = @import("Shader.zig");
 const errors = @import("errors.zig");
+const glad = @import("glad.zig");
 
 id: c.GLuint,
 
 const Binding = struct {
     pub inline fn unbind(_: Binding) void {
-        c.glUseProgram(0);
+        glad.context.UseProgram.?(0);
     }
 };
 
 pub inline fn create() !Program {
-    const id = c.glCreateProgram();
+    const id = glad.context.CreateProgram.?();
     if (id == 0) try errors.mustError();
 
     log.debug("program created id={}", .{id});
@@ -44,16 +45,16 @@ pub inline fn createVF(vsrc: [:0]const u8, fsrc: [:0]const u8) !Program {
 }
 
 pub inline fn attachShader(p: Program, s: Shader) !void {
-    c.glAttachShader(p.id, s.id);
+    glad.context.AttachShader.?(p.id, s.id);
     try errors.getError();
 }
 
 pub inline fn link(p: Program) !void {
-    c.glLinkProgram(p.id);
+    glad.context.LinkProgram.?(p.id);
 
     // Check if linking succeeded
     var success: c_int = undefined;
-    c.glGetProgramiv(p.id, c.GL_LINK_STATUS, &success);
+    glad.context.GetProgramiv.?(p.id, c.GL_LINK_STATUS, &success);
     if (success == c.GL_TRUE) {
         log.debug("program linked id={}", .{p.id});
         return;
@@ -67,7 +68,7 @@ pub inline fn link(p: Program) !void {
 }
 
 pub inline fn use(p: Program) !Binding {
-    c.glUseProgram(p.id);
+    glad.context.UseProgram.?(p.id);
     return Binding{};
 }
 
@@ -77,7 +78,7 @@ pub inline fn setUniform(
     n: [:0]const u8,
     value: anytype,
 ) !void {
-    const loc = c.glGetUniformLocation(
+    const loc = glad.context.GetUniformLocation.?(
         p.id,
         @ptrCast([*c]const u8, n.ptr),
     );
@@ -88,12 +89,12 @@ pub inline fn setUniform(
 
     // Perform the correct call depending on the type of the value.
     switch (@TypeOf(value)) {
-        comptime_int => c.glUniform1i(loc, value),
-        f32 => c.glUniform1f(loc, value),
-        @Vector(2, f32) => c.glUniform2f(loc, value[0], value[1]),
-        @Vector(3, f32) => c.glUniform3f(loc, value[0], value[1], value[2]),
-        @Vector(4, f32) => c.glUniform4f(loc, value[0], value[1], value[2], value[3]),
-        [4]@Vector(4, f32) => c.glUniformMatrix4fv(
+        comptime_int => glad.context.Uniform1i.?(loc, value),
+        f32 => glad.context.Uniform1f.?(loc, value),
+        @Vector(2, f32) => glad.context.Uniform2f.?(loc, value[0], value[1]),
+        @Vector(3, f32) => glad.context.Uniform3f.?(loc, value[0], value[1], value[2]),
+        @Vector(4, f32) => glad.context.Uniform4f.?(loc, value[0], value[1], value[2], value[3]),
+        [4]@Vector(4, f32) => glad.context.UniformMatrix4fv.?(
             loc,
             1,
             c.GL_FALSE,
@@ -112,12 +113,12 @@ pub inline fn setUniform(
 // if we ever need it.
 pub inline fn getInfoLog(s: Program) [512]u8 {
     var msg: [512]u8 = undefined;
-    c.glGetProgramInfoLog(s.id, msg.len, null, &msg);
+    glad.context.GetProgramInfoLog.?(s.id, msg.len, null, &msg);
     return msg;
 }
 
 pub inline fn destroy(p: Program) void {
     assert(p.id != 0);
-    c.glDeleteProgram(p.id);
+    glad.context.DeleteProgram.?(p.id);
     log.debug("program destroyed id={}", .{p.id});
 }

src/opengl/Shader.zig

@@ -6,11 +6,12 @@ const log = std.log.scoped(.opengl);
 
 const c = @import("c.zig");
 const errors = @import("errors.zig");
+const glad = @import("glad.zig");
 
 id: c.GLuint,
 
 pub inline fn create(typ: c.GLenum) errors.Error!Shader {
-    const id = c.glCreateShader(typ);
+    const id = glad.context.CreateShader.?(typ);
     if (id == 0) {
         try errors.mustError();
         unreachable;
@@ -22,12 +23,12 @@ pub inline fn create(typ: c.GLenum) errors.Error!Shader {
 
 /// Set the source and compile a shader.
 pub inline fn setSourceAndCompile(s: Shader, source: [:0]const u8) !void {
-    c.glShaderSource(s.id, 1, &@ptrCast([*c]const u8, source), null);
-    c.glCompileShader(s.id);
+    glad.context.ShaderSource.?(s.id, 1, &@ptrCast([*c]const u8, source), null);
+    glad.context.CompileShader.?(s.id);
 
     // Check if compilation succeeded
     var success: c_int = undefined;
-    c.glGetShaderiv(s.id, c.GL_COMPILE_STATUS, &success);
+    glad.context.GetShaderiv.?(s.id, c.GL_COMPILE_STATUS, &success);
     if (success == c.GL_TRUE) return;
     log.err("shader compilation failure id={} message={s}", .{
         s.id,
@@ -44,12 +45,12 @@ pub inline fn setSourceAndCompile(s: Shader, source: [:0]const u8) !void {
 // if we ever need it.
 pub inline fn getInfoLog(s: Shader) [512]u8 {
     var msg: [512]u8 = undefined;
-    c.glGetShaderInfoLog(s.id, msg.len, null, &msg);
+    glad.context.GetShaderInfoLog.?(s.id, msg.len, null, &msg);
     return msg;
 }
 
 pub inline fn destroy(s: Shader) void {
     assert(s.id != 0);
-    c.glDeleteShader(s.id);
+    glad.context.DeleteShader.?(s.id);
     log.debug("shader destroyed id={}", .{s.id});
 }

src/opengl/Texture.zig

@@ -3,11 +3,12 @@ const Texture = @This();
 const std = @import("std");
 const c = @import("c.zig");
 const errors = @import("errors.zig");
+const glad = @import("glad.zig");
 
 id: c.GLuint,
 
 pub inline fn active(target: c.GLenum) !void {
-    c.glActiveTexture(target);
+    glad.context.ActiveTexture.?(target);
 }
 
 /// Enun for possible texture binding targets.
@@ -74,17 +75,17 @@ pub const Binding = struct {
     target: Target,
 
     pub inline fn unbind(b: *Binding) void {
-        c.glBindTexture(@enumToInt(b.target), 0);
+        glad.context.BindTexture.?(@enumToInt(b.target), 0);
         b.* = undefined;
     }
 
     pub fn generateMipmap(b: Binding) void {
-        c.glGenerateMipmap(@enumToInt(b.target));
+        glad.context.GenerateMipmap.?(@enumToInt(b.target));
     }
 
     pub fn parameter(b: Binding, name: Parameter, value: anytype) !void {
         switch (@TypeOf(value)) {
-            c.GLint => c.glTexParameteri(
+            c.GLint => glad.context.TexParameteri.?(
                 @enumToInt(b.target),
                 @enumToInt(name),
                 value,
@@ -104,7 +105,7 @@ pub const Binding = struct {
         typ: DataType,
         data: ?*const anyopaque,
     ) !void {
-        c.glTexImage2D(
+        glad.context.TexImage2D.?(
             @enumToInt(b.target),
             level,
             @enumToInt(internal_format),
@@ -128,7 +129,7 @@ pub const Binding = struct {
         typ: DataType,
         data: ?*const anyopaque,
     ) !void {
-        c.glTexSubImage2D(
+        glad.context.TexSubImage2D.?(
             @enumToInt(b.target),
             level,
             xoffset,
@@ -145,16 +146,16 @@ pub const Binding = struct {
 /// Create a single texture.
 pub inline fn create() !Texture {
     var id: c.GLuint = undefined;
-    c.glGenTextures(1, &id);
+    glad.context.GenTextures.?(1, &id);
     return Texture{ .id = id };
 }
 
 /// glBindTexture
 pub inline fn bind(v: Texture, target: Target) !Binding {
-    c.glBindTexture(@enumToInt(target), v.id);
+    glad.context.BindTexture.?(@enumToInt(target), v.id);
     return Binding{ .target = target };
 }
 
 pub inline fn destroy(v: Texture) void {
-    c.glDeleteTextures(1, &v.id);
+    glad.context.DeleteTextures.?(1, &v.id);
 }

src/opengl/VertexArray.zig

@@ -1,26 +1,27 @@
 const VertexArray = @This();
 
 const c = @import("c.zig");
+const glad = @import("glad.zig");
 
 id: c.GLuint,
 
 /// Create a single vertex array object.
 pub inline fn create() !VertexArray {
     var vao: c.GLuint = undefined;
-    c.glGenVertexArrays(1, &vao);
+    glad.context.GenVertexArrays.?(1, &vao);
     return VertexArray{ .id = vao };
 }
 
 // Unbind any active vertex array.
 pub inline fn unbind() !void {
-    c.glBindVertexArray(0);
+    glad.context.BindVertexArray.?(0);
 }
 
 /// glBindVertexArray
 pub inline fn bind(v: VertexArray) !void {
-    c.glBindVertexArray(v.id);
+    glad.context.BindVertexArray.?(v.id);
 }
 
 pub inline fn destroy(v: VertexArray) void {
-    c.glDeleteVertexArrays(1, &v.id);
+    glad.context.DeleteVertexArrays.?(1, &v.id);
 }

src/opengl/draw.zig

@@ -1,22 +1,23 @@
 const c = @import("c.zig");
 const errors = @import("errors.zig");
+const glad = @import("glad.zig");
 
 pub fn clearColor(r: f32, g: f32, b: f32, a: f32) void {
-    c.glClearColor(r, g, b, a);
+    glad.context.ClearColor.?(r, g, b, a);
 }
 
 pub fn clear(mask: c.GLbitfield) void {
-    c.glClear(mask);
+    glad.context.Clear.?(mask);
 }
 
 pub fn drawArrays(mode: c.GLenum, first: c.GLint, count: c.GLsizei) !void {
-    c.glDrawArrays(mode, first, count);
+    glad.context.DrawArrays.?(mode, first, count);
     try errors.getError();
 }
 
 pub fn drawElements(mode: c.GLenum, count: c.GLsizei, typ: c.GLenum, offset: usize) !void {
     const offsetPtr = if (offset == 0) null else @intToPtr(*const anyopaque, offset);
-    c.glDrawElements(mode, count, typ, offsetPtr);
+    glad.context.DrawElements.?(mode, count, typ, offsetPtr);
     try errors.getError();
 }
 
@@ -26,17 +27,32 @@ pub fn drawElementsInstanced(
     typ: c.GLenum,
     primcount: usize,
 ) !void {
-    c.glDrawElementsInstanced(mode, count, typ, null, @intCast(c.GLsizei, primcount));
+    glad.context.DrawElementsInstanced.?(mode, count, typ, null, @intCast(c.GLsizei, primcount));
+    try errors.getError();
+}
+
+pub fn enable(cap: c.GLenum) !void {
+    glad.context.Enable.?(cap);
+    try errors.getError();
+}
+
+pub fn frontFace(mode: c.GLenum) !void {
+    glad.context.FrontFace.?(mode);
+    try errors.getError();
+}
+
+pub fn blendFunc(sfactor: c.GLenum, dfactor: c.GLenum) !void {
+    glad.context.BlendFunc.?(sfactor, dfactor);
     try errors.getError();
 }
 
 pub fn viewport(x: c.GLint, y: c.GLint, width: c.GLsizei, height: c.GLsizei) !void {
-    c.glViewport(x, y, width, height);
+    glad.context.Viewport.?(x, y, width, height);
 }
 
 pub fn pixelStore(mode: c.GLenum, value: anytype) !void {
     switch (@typeInfo(@TypeOf(value))) {
-        .ComptimeInt, .Int => c.glPixelStorei(mode, value),
+        .ComptimeInt, .Int => glad.context.PixelStorei.?(mode, value),
         else => unreachable,
     }
     try errors.getError();

src/opengl/errors.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const c = @import("c.zig");
+const glad = @import("glad.zig");
 
 pub const Error = error{
     InvalidEnum,
@@ -13,7 +14,7 @@ pub const Error = error{
 
 /// getError returns the error (if any) from the last OpenGL operation.
 pub fn getError() Error!void {
-    return switch (c.glGetError()) {
+    return switch (glad.context.GetError.?()) {
         c.GL_NO_ERROR => {},
         c.GL_INVALID_ENUM => Error.InvalidEnum,
         c.GL_INVALID_VALUE => Error.InvalidValue,

src/opengl/extensions.zig

@@ -1,11 +1,12 @@
 const std = @import("std");
 const c = @import("c.zig");
 const errors = @import("errors.zig");
+const glad = @import("glad.zig");
 
 /// Returns the number of extensions.
 pub fn len() !u32 {
     var n: c.GLint = undefined;
-    c.glGetIntegerv(c.GL_NUM_EXTENSIONS, &n);
+    glad.context.GetIntegerv.?(c.GL_NUM_EXTENSIONS, &n);
     try errors.getError();
     return @intCast(u32, n);
 }
@@ -23,7 +24,7 @@ pub const Iterator = struct {
 
     pub fn next(self: *Iterator) !?[]const u8 {
         if (self.i >= self.len) return null;
-        const res = c.glGetStringi(c.GL_EXTENSIONS, self.i);
+        const res = glad.context.GetStringi.?(c.GL_EXTENSIONS, self.i);
         try errors.getError();
         self.i += 1;
         return std.mem.sliceTo(res, 0);

src/opengl/glad.zig

@@ -1,6 +1,14 @@
 const std = @import("std");
 const c = @import("c.zig");
 
+pub const Context = c.GladGLContext;
+
+/// This is the current context. Set this var manually prior to calling
+/// any of this package's functions. I know its nasty to have a global but
+/// this makes it match OpenGL API styles where it also operates on a
+/// threadlocal global.
+pub threadlocal var context: Context = undefined;
+
 /// Initialize Glad. This is guaranteed to succeed if no errors are returned.
 /// The getProcAddress param is an anytype so that we can accept multiple
 /// forms of the function depending on what we're interfacing with.
@@ -10,18 +18,23 @@ pub fn load(getProcAddress: anytype) !c_int {
 
     const res = switch (@TypeOf(getProcAddress)) {
         // glfw
-        GlfwFn => c.gladLoadGL(@ptrCast(
+        GlfwFn => c.gladLoadGLContext(&context, @ptrCast(
             std.meta.FnPtr(fn ([*c]const u8) callconv(.C) ?GlProc),
             getProcAddress,
         )),
 
         // try as-is. If this introduces a compiler error, then add a new case.
-        else => c.gladLoadGL(getProcAddress),
+        else => c.gladLoadGLContext(&context, getProcAddress),
     };
     if (res == 0) return error.GLInitFailed;
     return res;
 }
 
+pub fn unload() void {
+    c.gladLoaderUnloadGLContext(&context);
+    context = undefined;
+}
+
 pub fn versionMajor(res: c_int) c_uint {
     // https://github.com/ziglang/zig/issues/13162
     // return c.GLAD_VERSION_MAJOR(res);