--- src/gl_manager.cc.orig	2026-04-27 01:16:06.062228168 +0000
+++ src/gl_manager.cc	2026-04-27 01:16:46.121276893 +0000
@@ -45,6 +45,25 @@
   return Error::New();
 }
 
+// GL 2.0/2.1 compatible shaders (GLSL 1.20)
+static const char vertex_source_gl2[] =
+  "#version 120\n"
+  "attribute vec2 in_position;"
+  "attribute vec2 in_texpos;"
+  "varying vec2 texpos;"
+  "void main() {"
+    "gl_Position = vec4(in_position, 0.0, 1.0);"
+    "texpos = in_texpos;"
+  "}";
+
+static const char fragment_source_gl2[] =
+  "#version 120\n"
+  "uniform sampler2D tex;"
+  "varying vec2 texpos;"
+  "void main() {"
+    "gl_FragColor = texture2D(tex, texpos);"
+  "}";
+
 static const char vertex_source[] =
   "#version 330 core\n"
 
@@ -87,13 +106,26 @@
 Error GLManager::Initialize(int width, int height) {
   glClearColor(1, 1, 1, 0);
 
+  // Detect GL version to choose appropriate shaders
+  const char* gl_version = reinterpret_cast<const char*>(glGetString(GL_VERSION));
+  m_use_gl2 = false;
+  if (gl_version) {
+    int major = 0;
+    if (sscanf(gl_version, "%d", &major) == 1 && major < 3) {
+      m_use_gl2 = true;
+    }
+  }
+
+  const char* vert_src = m_use_gl2 ? vertex_source_gl2 : vertex_source;
+  const char* frag_src = m_use_gl2 ? fragment_source_gl2 : fragment_source;
+
   *m_vertex.id_ptr() = glCreateShader(GL_VERTEX_SHADER);
-  if (auto err = CompileShader(m_vertex.id(), vertex_source)) {
+  if (auto err = CompileShader(m_vertex.id(), vert_src)) {
     return err.Extend("while compiling vertex shader");
   }
 
   *m_fragment.id_ptr() = glCreateShader(GL_FRAGMENT_SHADER);
-  if (auto err = CompileShader(m_fragment.id(), fragment_source)) {
+  if (auto err = CompileShader(m_fragment.id(), frag_src)) {
     return err.Extend("while compiling fragment shader");
   }
 
@@ -117,18 +149,31 @@
 
   constexpr GLsizei stride = sizeof(float) * 4;
 
-  glGenVertexArrays(1, m_vao.id_ptr());
+  // VAOs are required in GL 3.2+ Core Profile but optional in GL 2.x
+  m_have_vao = !m_use_gl2 || epoxy_has_gl_extension("GL_APPLE_vertex_array_object") ||
+                             epoxy_has_gl_extension("GL_ARB_vertex_array_object");
+  if (m_have_vao) {
+    glGenVertexArrays(1, m_vao.id_ptr());
+    glBindVertexArray(m_vao.id());
+  }
+
   glGenBuffers(1, m_vbo.id_ptr());
   glGenBuffers(1, m_ebo.id_ptr());
 
-  glBindVertexArray(m_vao.id());
-
   glBindBuffer(GL_ARRAY_BUFFER, m_vbo.id());
   glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
   glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ebo.id());
   glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
 
+  // For GL 2.x, bind attribute locations manually before linking
+  if (m_use_gl2) {
+    glBindAttribLocation(m_program.id(), 0, "in_position");
+    glBindAttribLocation(m_program.id(), 1, "in_texpos");
+    // Re-link after binding attributes
+    glLinkProgram(m_program.id());
+  }
+
   glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, stride, reinterpret_cast<void*>(0));
   glEnableVertexAttribArray(0);
 
@@ -165,6 +210,17 @@
   glBindTexture(GL_TEXTURE_2D, m_texture.id());
 
   glUseProgram(m_program.id());
-  glBindVertexArray(m_vao.id());
+  if (m_have_vao) {
+    glBindVertexArray(m_vao.id());
+  } else {
+    // Rebind vertex attributes each frame for GL 2.x without VAO
+    constexpr GLsizei stride = sizeof(float) * 4;
+    glBindBuffer(GL_ARRAY_BUFFER, m_vbo.id());
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, stride, reinterpret_cast<void*>(0));
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, stride, reinterpret_cast<void*>(sizeof(float) * 2));
+    glEnableVertexAttribArray(1);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ebo.id());
+  }
   glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 }