Check for required extensions

kitty/develop_gl.py

@@ -6,7 +6,7 @@ import glfw
 import OpenGL.GL as gl
 import sys
 
-from kitty.shaders import ShaderProgram, GL_VERSION, Sprites
+from kitty.shaders import ShaderProgram, GL_VERSION, Sprites, check_for_required_extensions
 from kitty.fonts import set_font_family, cell_size
 
 textured_shaders = (
@@ -148,6 +148,7 @@ def _main():
         raise SystemExit("glfwCreateWindow failed")
     glfw.glfwMakeContextCurrent(window)
     glfw.glfwSwapInterval(1)
+    check_for_required_extensions()
 
     # If everything went well the following calls
     # will display the version of opengl being used

kitty/main.py

@@ -13,7 +13,7 @@ from .config import load_config
 from .constants import appname, str_version, config_dir
 from .boss import Boss
 from .utils import fork_child, hangup
-from .shaders import GL_VERSION
+from .shaders import GL_VERSION, check_for_required_extensions
 import glfw
 
 
@@ -52,6 +52,7 @@ def run_app(opts, args):
     glfw.glfwSetWindowTitle(window, appname.encode('utf-8'))
     try:
         glfw.glfwMakeContextCurrent(window)
+        check_for_required_extensions()
         glfw.glfwSwapInterval(1)
         boss = Boss(window, window_width, window_height, opts, args)
         glfw.glfwSetFramebufferSizeCallback(window, boss.on_window_resize)

kitty/shaders.py

@@ -13,12 +13,25 @@ from .fonts import render_cell, cell_size
 
 GL_VERSION = (3, 3)
 VERSION = GL_VERSION[0] * 100 + GL_VERSION[1] * 10
+REQUIRED_EXTENSIONS = frozenset('GL_ARB_copy_image GL_ARB_texture_storage'.split())
 
 
 def array(*args, dtype=gl.GLfloat):
     return (dtype * len(args))(*args)
 
 
+def check_for_required_extensions():
+    num = gl.glGetIntegerv(gl.GL_NUM_EXTENSIONS)
+    required = set(REQUIRED_EXTENSIONS)
+    for i in range(num):
+        ext = gl.glGetStringi(gl.GL_EXTENSIONS, i).decode('utf-8')
+        required.discard(ext)
+        if not required:
+            break
+    if required:
+        raise RuntimeError('Your OpenGL implementation is missing the following required extensions: %s' % ','.join(required))
+
+
 class Sprites:
     ''' Maintain sprite sheets of all rendered characters on the GPU as a texture
     array with each texture being a sprite sheet. '''