🚚 Move shader code to GLSL files

resources/shaders/common/uniforms.glsl

@@ -0,0 +1,11 @@
+// These should be included in every shader.
+// uForOpening: True if a window-open animation is ongoing, false otherwise.
+// uTexture:    Contains the texture of the window.
+// uProgress:   A value which transitions from 0 to 1 during the entire animation.
+// uTime:       A steadily increasing value in seconds.
+// uSize:       The size of uTexture in pixels.
+uniform bool uForOpening;
+uniform sampler2D uTexture;
+uniform float uProgress;
+uniform float uTime;
+uniform vec2 uSize;