1 files changed, 63 insertions, 14 deletions
diff --git a/doc/python_api/examples/gpu.7.py b/doc/python_api/examples/gpu.7.py
index 69af65e163e..56cbb93c61a 100644
--- a/doc/python_api/examples/gpu.7.py
+++ b/doc/python_api/examples/gpu.7.py
@@ -1,37 +1,86 @@
 """
-2D Image
---------
+Generate a texture using Offscreen Rendering
+--------------------------------------------
 
-To use this example you have to provide an image that should be displayed.
+#. Create an :class:`gpu.types.GPUOffScreen` object.
+#. Draw some circles into it.
+#. Make a new shader for drawing a planar texture in 3D.
+#. Draw the generated texture using the new shader.
 """
 import bpy
 import gpu
 import bgl
+from mathutils import Matrix
 from gpu_extras.batch import batch_for_shader
+from gpu_extras.presets import draw_circle_2d
 
-IMAGE_NAME = "Untitled"
-image = bpy.data.images[IMAGE_NAME]
+# Create and fill offscreen
+##########################################
 
-shader = gpu.shader.from_builtin('2D_IMAGE')
+offscreen = gpu.types.GPUOffScreen(512, 512)
+
+with offscreen.bind():
+    bgl.glClear(bgl.GL_COLOR_BUFFER_BIT)
+    with gpu.matrix.push_pop():
+        # reset matrices -> use normalized device coordinates [-1, 1]
+        gpu.matrix.load_matrix(Matrix.Identity(4))
+        gpu.matrix.load_projection_matrix(Matrix.Identity(4))
+
+        amount = 10
+        for i in range(-amount, amount + 1):
+            x_pos = i / amount
+            draw_circle_2d((x_pos, 0.0), (1, 1, 1, 1), 0.5, 200)
+
+
+# Drawing the generated texture in 3D space
+#############################################
+
+vertex_shader = '''
+    uniform mat4 modelMatrix;
+    uniform mat4 viewProjectionMatrix;
+
+    in vec2 position;
+    in vec2 uv;
+
+    out vec2 uvInterp;
+
+    void main()
+    {
+        uvInterp = uv;
+        gl_Position = viewProjectionMatrix * modelMatrix * vec4(position, 0.0, 1.0);
+    }
+'''
+
+fragment_shader = '''
+    uniform sampler2D image;
+
+    in vec2 uvInterp;
+
+    void main()
+    {
+        gl_FragColor = texture(image, uvInterp);
+    }
+'''
+
+shader = gpu.types.GPUShader(vertex_shader, fragment_shader)
 batch = batch_for_shader(
     shader, 'TRI_FAN',
     {
-        "pos": ((100, 100), (200, 100), (200, 200), (100, 200)),
-        "texCoord": ((0, 0), (1, 0), (1, 1), (0, 1)),
+        "position": ((-1, -1), (1, -1), (1, 1), (-1, 1)),
+        "uv": ((0, 0), (1, 0), (1, 1), (0, 1)),
     },
 )
 
-if image.gl_load():
-    raise Exception()
-
 
 def draw():
     bgl.glActiveTexture(bgl.GL_TEXTURE0)
-    bgl.glBindTexture(bgl.GL_TEXTURE_2D, image.bindcode)
+    bgl.glBindTexture(bgl.GL_TEXTURE_2D, offscreen.color_texture)
 
     shader.bind()
-    shader.uniform_int("image", 0)
+    shader.uniform_float("modelMatrix", Matrix.Translation((1, 2, 3)) @ Matrix.Scale(3, 4))
+    shader.uniform_float("viewProjectionMatrix", bpy.context.region_data.perspective_matrix)
+    shader.uniform_float("image", 0)
     batch.draw(shader)
 
 
-bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_PIXEL')
+bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW')