Add tests for offscreen and snapshot

tests/test_util_shadertoy.py

@@ -66,3 +66,56 @@ 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