Class to manage shaders

kitty/shaders.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
+
+from functools import lru_cache
+
+from OpenGL.GL import (
+    glCreateProgram, GL_VERTEX_SHADER, GL_FRAGMENT_SHADER, glAttachShader,
+    glLinkProgram, glGetProgramiv, glGetProgramInfoLog, GL_LINK_STATUS,
+    GL_TRUE, glDeleteProgram, glDeleteShader, glCreateShader, glCompileShader,
+    glGetShaderiv, GL_COMPILE_STATUS, glShaderSource, glGetShaderInfoLog,
+    glGetUniformLocation, glGetAttribLocation
+)
+
+
+class ShaderProgram:
+    """ Helper class for using GLSL shader programs """
+
+    def __init__(self, vertex: str, fragment: str):
+        """
+        Create a shader program.
+
+        :param vertex: The vertex shader
+        :param fragment: The fragment shader
+
+        """
+        self.program_id = glCreateProgram()
+        vs_id = self.add_shader(vertex, GL_VERTEX_SHADER)
+        frag_id = self.add_shader(fragment, GL_FRAGMENT_SHADER)
+
+        glAttachShader(self.program_id, vs_id)
+        glAttachShader(self.program_id, frag_id)
+        glLinkProgram(self.program_id)
+
+        if glGetProgramiv(self.program_id, GL_LINK_STATUS) != GL_TRUE:
+            info = glGetProgramInfoLog(self.program_id)
+            glDeleteProgram(self.program_id)
+            glDeleteShader(vs_id)
+            glDeleteShader(frag_id)
+            raise ValueError('Error linking shader program: %s' % info)
+        glDeleteShader(vs_id)
+        glDeleteShader(frag_id)
+
+    def __hash__(self):
+        return self.program_id
+
+    def __eq__(self, other):
+        return isinstance(other, ShaderProgram) and other.program_id == self.program_id
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def add_shader(self, source: str, shader_type: int):
+        ' Compile a shader and return its id, or raise an exception if compilation fails '
+        shader_id = glCreateShader(shader_type)
+        try:
+            glShaderSource(shader_id, source)
+            glCompileShader(shader_id)
+            if glGetShaderiv(shader_id, GL_COMPILE_STATUS) != GL_TRUE:
+                info = glGetShaderInfoLog(shader_id)
+                raise ValueError('GLSL Shader compilation failed: %s' % info)
+            return shader_id
+        except Exception:
+            glDeleteShader(shader_id)
+            raise
+
+    @lru_cache(maxlen=None)
+    def uniform_location(self, name: str):
+        ' Return the id for the uniform variable `name` or -1 if not found. '
+        return glGetUniformLocation(self.program_id, name)
+
+    @lru_cache(maxlen=None)
+    def attribute_location(self, name: str):
+        ' Return the id for the attribute variable `name` or -1 if not found. '
+        return glGetAttribLocation(self.program_id, name)