opengl: bound buffers

src/main.zig

@@ -55,8 +55,8 @@ pub fn main() !void {
     const vbo = try gl.Buffer.create();
     defer vbo.destroy();
     try vao.bind();
-    try vbo.bind(c.GL_ARRAY_BUFFER);
-    try vbo.setData(c.GL_ARRAY_BUFFER, vertices, c.GL_STATIC_DRAW);
+    var binding = try vbo.bind(c.GL_ARRAY_BUFFER);
+    try binding.setData(&vertices, c.GL_STATIC_DRAW);
 
     c.glVertexAttribPointer(
         0,
@@ -68,7 +68,7 @@ pub fn main() !void {
     );
     c.glEnableVertexAttribArray(0);
 
-    try gl.Buffer.unbind(c.GL_ARRAY_BUFFER);
+    binding.unbind();
     try gl.VertexArray.unbind();
 
     // Wait for the user to close the window.

src/opengl/Buffer.zig

@@ -6,33 +6,19 @@ const errors = @import("errors.zig");
 
 id: c.GLuint,
 
-/// Create a single buffer.
-pub inline fn create() !Buffer {
-    var vbo: c.GLuint = undefined;
-    c.glGenBuffers(1, &vbo);
-    return Buffer{ .id = vbo };
-}
-
-// Unbind any active vertex array.
-pub inline fn unbind(target: c.GLenum) !void {
-    c.glBindBuffer(target, 0);
-}
-
-/// glBindBuffer
-pub inline fn bind(v: Buffer, target: c.GLenum) !void {
-    c.glBindBuffer(target, v.id);
-}
-
-pub inline fn setData(
-    v: Buffer,
+/// Binding is a bound buffer. By using this for functions that operate
+/// on bound buffers, you can easily defer unbinding and in safety-enabled
+/// modes verify that unbound buffers are never accessed.
+pub const Binding = struct {
     target: c.GLenum,
+
+    /// Sets the data of this bound buffer. The data can be any array-like
+    /// type. The size of the data is automatically determined based on the type.
+    pub inline fn setData(
+        b: Binding,
         data: anytype,
         usage: c.GLenum,
     ) !void {
-    // Maybe one day in debug mode we can validate that this buffer
-    // is currently bound.
-    _ = v;
-
         // Determine the size and pointer to the given data.
         const info: struct {
             size: isize,
@@ -62,10 +48,32 @@ pub inline fn setData(
             },
         };
 
-    c.glBufferData(target, info.size, info.ptr, usage);
+        c.glBufferData(b.target, info.size, info.ptr, usage);
         try errors.getError();
     }
 
+    pub inline fn unbind(b: *Binding) void {
+        c.glBindBuffer(b.target, 0);
+
+        // By setting this to undefined, this ensures that any future calls
+        // error in safe build modes.
+        b.* = undefined;
+    }
+};
+
+/// Create a single buffer.
+pub inline fn create() !Buffer {
+    var vbo: c.GLuint = undefined;
+    c.glGenBuffers(1, &vbo);
+    return Buffer{ .id = vbo };
+}
+
+/// glBindBuffer
+pub inline fn bind(v: Buffer, target: c.GLenum) !Binding {
+    c.glBindBuffer(target, v.id);
+    return Binding{ .target = target };
+}
+
 pub inline fn destroy(v: Buffer) void {
     c.glDeleteBuffers(1, &v.id);
 }