Check for required extensions

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. '''