"""
Simple Render Engine
++++++++++++++++++++
"""

import bpy


class CustomRenderEngine(bpy.types.RenderEngine):
    # These three members are used by blender to set up the
    # RenderEngine; define its internal name, visible name and capabilities.
    bl_idname = 'custom_renderer'
    bl_label = 'Flat Color Renderer'
    bl_use_preview = True

    # This is the only method called by blender, in this example
    # we use it to detect preview rendering and call the implementation
    # in another method.
    def render(self, scene):
        scale = scene.render.resolution_percentage / 100.0
        self.size_x = int(scene.render.resolution_x * scale)
        self.size_y = int(scene.render.resolution_y * scale)

        if scene.name == 'preview':
            self.render_preview(scene)
        else:
            self.render_scene(scene)

    # In this example, we fill the preview renders with a flat green color.
    def render_preview(self, scene):
        pixel_count = self.size_x * self.size_y

        # The framebuffer is defined as a list of pixels, each pixel
        # itself being a list of R,G,B,A values
        green_rect = [[0.0, 1.0, 0.0, 1.0]] * pixel_count

        # Here we write the pixel values to the RenderResult
        result = self.begin_result(0, 0, self.size_x, self.size_y)
        layer = result.layers[0]
        layer.rect = green_rect
        self.end_result(result)

    # In this example, we fill the full renders with a flat blue color.
    def render_scene(self, scene):
        pixel_count = self.size_x * self.size_y

        # The framebuffer is defined as a list of pixels, each pixel
        # itself being a list of R,G,B,A values
        blue_rect = [[0.0, 0.0, 1.0, 1.0]] * pixel_count

        # Here we write the pixel values to the RenderResult
        result = self.begin_result(0, 0, self.size_x, self.size_y)
        layer = result.layers[0]
        layer.rect = blue_rect
        self.end_result(result)

# Register the RenderEngine
bpy.utils.register_class(CustomRenderEngine)

# RenderEngines also need to tell UI Panels that they are compatible
# Otherwise most of the UI will be empty when the engine is selected.
# In this example, we need to see the main render image button and
# the material preview panel.
from bl_ui import properties_render
properties_render.RENDER_PT_render.COMPAT_ENGINES.add('custom_renderer')
del properties_render

from bl_ui import properties_material
properties_material.MATERIAL_PT_preview.COMPAT_ENGINES.add('custom_renderer')
del properties_material