make opengl loader context-aware

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);
 }