Support for runtime reloading of shaders

Author: einarf

README.rst

@@ -56,6 +56,7 @@ Features
 - Management commands to create new projects and effects
 - Convenient wrappers for VAO, Shader, Texture, FBO
 - On-the-fly Shader and VAO negotiation of the needed buffer binding
+- Runtime re-loading shaders (press R)
 - Strict validation in most OpenGL operations with reasonable error feedback
 - Time line / Timer support
 - A highly pluggable framework

demosys/opengl/shader.py

@@ -112,14 +112,33 @@ def prepare(self):
         Compiles all the shaders and links the program.
         If the linking is successful, it builds the uniform and attribute map.
         """
+        # Attempt to delete the current shader in case we are re-loading
+        self.delete()
+
+        # Compile the separate shaders
         self.vert_source.compile()
         self.frag_source.compile()
         if self.geo_source:
             self.geo_source.compile()
         self.link()
+
+        # Build internal lookups
         self.build_uniform_map()
         self.build_attribute_map()
 
+        # We only need the programs for linking
+        if self.vert_source:
+            self.vert_source.delete(self.program)
+        if self.frag_source:
+            self.frag_source.delete(self.program)
+        if self.geo_source:
+            self.geo_source.delete(self.program)
+
+    def delete(self):
+        """Frees the memory and invalidates the name associated with the program"""
+        if self.program:
+            GL.glDeleteProgram(self.program)
+
     def link(self):
         """
         Links the program.
@@ -753,6 +772,14 @@ def compile(self):
             self.print()
             raise ShaderError("Failed to compile {} {}: {}".format(self.type_name(), self.name, message.decode()))
 
+    def delete(self, program=None):
+        """Frees the memory and invalidates the name associated with the shader object """
+        # The shader will not be deleted if attached
+        if program:
+            GL.glDetachShader(program, self.shader)
+        # Now we can delete it
+        GL.glDeleteShader(self.shader)
+
     def print(self):
         """Print the shader lines"""
         print("---[ START {} ]---".format(self.name))

demosys/view/controller.py

@@ -165,6 +165,9 @@ def key_event_callback(window, key, scancode, action, mods):
     if key == glfw.KEY_X and action == glfw.PRESS:
         screenshot.create()
 
+    if key == glfw.KEY_R and action == glfw.PRESS:
+        resources.shaders.load()
+
     # Forward the event to the effect manager
     MANAGER.key_event(key, scancode, action, mods)
 

docs/source/controls.rst

@@ -23,6 +23,7 @@ Simply apply the ``view_matrix`` of the camera to your transformations.
 - ``D`` strafe right
 - ``Q`` down the y axis
 - ``E`` up the y axis
+- ``R`` reload all shaders
 
 **Mouse Controls**