From 3c978a73d1ffc287263b371a6a7e9b38cb169f45 Mon Sep 17 00:00:00 2001
From: Germano Cavalcante <germano.costa@ig.com.br>
Date: Sun, 2 May 2021 16:30:23 -0300
Subject: [PATCH] Docs: PyAPI: Replace use of the bgl module in the
 RenderEngine example

The bgl module will be discontinued.

This example is seen at:
https://docs.blender.org/api/current/bpy.types.RenderEngine.html uses it.

Differential Revision: https://developer.blender.org/D11262
---
 .../examples/bpy.types.RenderEngine.py        | 72 ++++---------------
 1 file changed, 13 insertions(+), 59 deletions(-)

diff --git a/doc/python_api/examples/bpy.types.RenderEngine.py b/doc/python_api/examples/bpy.types.RenderEngine.py
index 45910194244..0b8795340ad 100644
--- a/doc/python_api/examples/bpy.types.RenderEngine.py
+++ b/doc/python_api/examples/bpy.types.RenderEngine.py
@@ -4,7 +4,9 @@ Simple Render Engine
 """
 
 import bpy
-import bgl
+import array
+import gpu
+from gpu_extras.presets import draw_texture_2d
 
 
 class CustomRenderEngine(bpy.types.RenderEngine):
@@ -100,8 +102,7 @@ class CustomRenderEngine(bpy.types.RenderEngine):
         dimensions = region.width, region.height
 
         # Bind shader that converts from scene linear to display space,
-        bgl.glEnable(bgl.GL_BLEND)
-        bgl.glBlendFunc(bgl.GL_ONE, bgl.GL_ONE_MINUS_SRC_ALPHA)
+        gpu.state.blend_set('ALPHA_PREMULT')
         self.bind_display_space_shader(scene)
 
         if not self.draw_data or self.draw_data.dimensions != dimensions:
@@ -110,7 +111,7 @@ class CustomRenderEngine(bpy.types.RenderEngine):
         self.draw_data.draw()
 
         self.unbind_display_space_shader()
-        bgl.glDisable(bgl.GL_BLEND)
+        gpu.state.blend_set('NONE')
 
 
 class CustomDrawData:
@@ -119,68 +120,21 @@ class CustomDrawData:
         self.dimensions = dimensions
         width, height = dimensions
 
-        pixels = [0.1, 0.2, 0.1, 1.0] * width * height
-        pixels = bgl.Buffer(bgl.GL_FLOAT, width * height * 4, pixels)
+        pixels = width * height * array.array('f', [0.1, 0.2, 0.1, 1.0])
+        pixels = gpu.types.Buffer('FLOAT', width * height * 4, pixels)
 
         # Generate texture
-        self.texture = bgl.Buffer(bgl.GL_INT, 1)
-        bgl.glGenTextures(1, self.texture)
-        bgl.glActiveTexture(bgl.GL_TEXTURE0)
-        bgl.glBindTexture(bgl.GL_TEXTURE_2D, self.texture[0])
-        bgl.glTexImage2D(bgl.GL_TEXTURE_2D, 0, bgl.GL_RGBA16F, width, height, 0, bgl.GL_RGBA, bgl.GL_FLOAT, pixels)
-        bgl.glTexParameteri(bgl.GL_TEXTURE_2D, bgl.GL_TEXTURE_MIN_FILTER, bgl.GL_LINEAR)
-        bgl.glTexParameteri(bgl.GL_TEXTURE_2D, bgl.GL_TEXTURE_MAG_FILTER, bgl.GL_LINEAR)
-        bgl.glBindTexture(bgl.GL_TEXTURE_2D, 0)
+        self.texture = gpu.types.GPUTexture((width, height), format='RGBA16F', data=pixels)
 
-        # Bind shader that converts from scene linear to display space,
-        # use the scene's color management settings.
-        shader_program = bgl.Buffer(bgl.GL_INT, 1)
-        bgl.glGetIntegerv(bgl.GL_CURRENT_PROGRAM, shader_program)
-
-        # Generate vertex array
-        self.vertex_array = bgl.Buffer(bgl.GL_INT, 1)
-        bgl.glGenVertexArrays(1, self.vertex_array)
-        bgl.glBindVertexArray(self.vertex_array[0])
-
-        texturecoord_location = bgl.glGetAttribLocation(shader_program[0], "texCoord")
-        position_location = bgl.glGetAttribLocation(shader_program[0], "pos")
-
-        bgl.glEnableVertexAttribArray(texturecoord_location)
-        bgl.glEnableVertexAttribArray(position_location)
-
-        # Generate geometry buffers for drawing textured quad
-        position = [0.0, 0.0, width, 0.0, width, height, 0.0, height]
-        position = bgl.Buffer(bgl.GL_FLOAT, len(position), position)
-        texcoord = [0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0]
-        texcoord = bgl.Buffer(bgl.GL_FLOAT, len(texcoord), texcoord)
-
-        self.vertex_buffer = bgl.Buffer(bgl.GL_INT, 2)
-
-        bgl.glGenBuffers(2, self.vertex_buffer)
-        bgl.glBindBuffer(bgl.GL_ARRAY_BUFFER, self.vertex_buffer[0])
-        bgl.glBufferData(bgl.GL_ARRAY_BUFFER, 32, position, bgl.GL_STATIC_DRAW)
-        bgl.glVertexAttribPointer(position_location, 2, bgl.GL_FLOAT, bgl.GL_FALSE, 0, None)
-
-        bgl.glBindBuffer(bgl.GL_ARRAY_BUFFER, self.vertex_buffer[1])
-        bgl.glBufferData(bgl.GL_ARRAY_BUFFER, 32, texcoord, bgl.GL_STATIC_DRAW)
-        bgl.glVertexAttribPointer(texturecoord_location, 2, bgl.GL_FLOAT, bgl.GL_FALSE, 0, None)
-
-        bgl.glBindBuffer(bgl.GL_ARRAY_BUFFER, 0)
-        bgl.glBindVertexArray(0)
+        # Note: This is just a didactic example.
+        # In this case it would be more convenient to fill the texture with:
+        # self.texture.clear('FLOAT', value=[0.1, 0.2, 0.1, 1.0])
 
     def __del__(self):
-        bgl.glDeleteBuffers(2, self.vertex_buffer)
-        bgl.glDeleteVertexArrays(1, self.vertex_array)
-        bgl.glBindTexture(bgl.GL_TEXTURE_2D, 0)
-        bgl.glDeleteTextures(1, self.texture)
+        del self.texture
 
     def draw(self):
-        bgl.glActiveTexture(bgl.GL_TEXTURE0)
-        bgl.glBindTexture(bgl.GL_TEXTURE_2D, self.texture[0])
-        bgl.glBindVertexArray(self.vertex_array[0])
-        bgl.glDrawArrays(bgl.GL_TRIANGLE_FAN, 0, 4)
-        bgl.glBindVertexArray(0)
-        bgl.glBindTexture(bgl.GL_TEXTURE_2D, 0)
+        draw_texture_2d(self.texture, (0, 0), self.texture.width, self.texture.height)
 
 
 # RenderEngines also need to tell UI Panels that they are compatible with.