Improve Shadertoy Utility (#401)

* Add offscreen support

* Add snapshot method

* Add shadercode validation for glsl

* Remove unneeded dependencies

* Add additional validation with wgsl translation

* Add tests for offscreen and snapshot

* Revert external validation

* Fix style

* Fix docstring typos

---------

Co-authored-by: Korijn van Golen <[email protected]>

tests/test_util_shadertoy.py

@@ -66,3 +66,90 @@ def test_shadertoy_glsl():
     assert shader.shader_type == "glsl"
 
     shader._draw_frame()
+
+
+def test_shadertoy_offscreen():
+    # Import here, because it imports the wgpu.gui.auto
+    from wgpu.utils.shadertoy import Shadertoy  # noqa
+
+    shader_code = """
+        void shader_main(out vec4 fragColor, vec2 frag_coord) {
+            vec2 uv = frag_coord / i_resolution.xy;
+
+            if ( length(frag_coord - i_mouse.xy) < 20.0 ) {
+                fragColor = vec4(0.0, 0.0, 0.0, 1.0);
+            }else{
+                fragColor = vec4( 0.5 + 0.5 * sin(i_time * vec3(uv, 1.0) ), 1.0);
+            }
+
+        }
+    """
+
+    shader = Shadertoy(shader_code, resolution=(800, 450), offscreen=True)
+    assert shader.resolution == (800, 450)
+    assert shader.shader_code == shader_code
+    assert shader.shader_type == "glsl"
+    assert shader._offscreen is True
+
+
+def test_shadertoy_snapshot():
+    # Import here, because it imports the wgpu.gui.auto
+    from wgpu.utils.shadertoy import Shadertoy  # noqa
+
+    shader_code = """
+        void shader_main(out vec4 fragColor, vec2 frag_coord) {
+            vec2 uv = frag_coord / i_resolution.xy;
+
+            if ( length(frag_coord - i_mouse.xy) < 20.0 ) {
+                fragColor = vec4(0.0, 0.0, 0.0, 1.0);
+            }else{
+                fragColor = vec4( 0.5 + 0.5 * sin(i_time * vec3(uv, 1.0) ), 1.0);
+            }
+
+        }
+    """
+
+    shader = Shadertoy(shader_code, resolution=(800, 450), offscreen=True)
+    frame1a = shader.snapshot(
+        time_float=0.0,
+        mouse_pos=(
+            0,
+            0,
+            0,
+            0,
+        ),
+    )
+    frame2a = shader.snapshot(
+        time_float=1.2,
+        mouse_pos=(
+            100,
+            200,
+            0,
+            0,
+        ),
+    )
+    frame1b = shader.snapshot(
+        time_float=0.0,
+        mouse_pos=(
+            0,
+            0,
+            0,
+            0,
+        ),
+    )
+    frame2b = shader.snapshot(
+        time_float=1.2,
+        mouse_pos=(
+            100,
+            200,
+            0,
+            0,
+        ),
+    )
+
+    assert shader.resolution == (800, 450)
+    assert shader.shader_code == shader_code
+    assert shader.shader_type == "glsl"
+    assert shader._offscreen is True
+    assert frame1a == frame1b
+    assert frame2a == frame2b

wgpu/utils/shadertoy.py

@@ -3,7 +3,7 @@
 
 import wgpu
 from wgpu.gui.auto import WgpuCanvas, run
-
+from wgpu.gui.offscreen import WgpuCanvas as OffscreenCanvas, run as run_offscreen
 
 vertex_code_glsl = """
 #version 450 core
@@ -222,6 +222,7 @@ class Shadertoy:
     Parameters:
         shader_code (str): The shader code to use.
         resolution (tuple): The resolution of the shadertoy.
+        offscreen (bool): Whether to render offscreen. Default is False.
 
     The shader code must contain a entry point function:
 
@@ -247,7 +248,7 @@ class Shadertoy:
     # todo: support input textures
     # todo: support multiple render passes (`i_channel0`, `i_channel1`, etc.)
 
-    def __init__(self, shader_code, resolution=(800, 450)) -> None:
+    def __init__(self, shader_code, resolution=(800, 450), offscreen=False) -> None:
         self._uniform_data = UniformArray(
             ("mouse", "f", 4),
             ("resolution", "f", 3),
@@ -259,6 +260,8 @@ def __init__(self, shader_code, resolution=(800, 450)) -> None:
         self._shader_code = shader_code
         self._uniform_data["resolution"] = resolution + (1,)
 
+        self._offscreen = offscreen
+
         self._prepare_render()
         self._bind_events()
 
@@ -288,7 +291,14 @@ def shader_type(self):
     def _prepare_render(self):
         import wgpu.backends.rs  # noqa
 
-        self._canvas = WgpuCanvas(title="Shadertoy", size=self.resolution, max_fps=60)
+        if self._offscreen:
+            self._canvas = OffscreenCanvas(
+                title="Shadertoy", size=self.resolution, max_fps=60
+            )
+        else:
+            self._canvas = WgpuCanvas(
+                title="Shadertoy", size=self.resolution, max_fps=60
+            )
 
         adapter = wgpu.request_adapter(
             canvas=self._canvas, power_preference="high-performance"
@@ -463,7 +473,32 @@ def _draw_frame(self):
 
     def show(self):
         self._canvas.request_draw(self._draw_frame)
-        run()
+        if self._offscreen:
+            run_offscreen()
+        else:
+            run()
+
+    def snapshot(self, time_float: float = 0.0, mouse_pos: tuple = (0, 0, 0, 0)):
+        """
+        Returns an image of the specified time. (Only available when ``offscreen=True``)
+
+        Parameters:
+            time_float (float): The time to snapshot. It essentially sets ``i_time`` to a specific number. (Default is 0.0)
+            mouse_pos (tuple): The mouse position in pixels in the snapshot. It essentially sets ``i_mouse`` to a 4-tuple. (Default is (0,0,0,0))
+        Returns:
+            frame (memoryview): snapshot with transparancy. This object can be converted to a numpy array (without copying data)
+        using ``np.asarray(arr)``
+        """
+        if not self._offscreen:
+            raise NotImplementedError("Snapshot is only available in offscreen mode.")
+
+        if hasattr(self, "_last_time"):
+            self.__delattr__("_last_time")
+        self._uniform_data["time"] = time_float
+        self._uniform_data["mouse"] = mouse_pos
+        self._canvas.request_draw(self._draw_frame)
+        frame = self._canvas.draw()
+        return frame
 
 
 if __name__ == "__main__":