Create/Update assets for version 1.13

assets/minecraft/shaders/program/invert.fsh

@@ -0,0 +1,14 @@
+#version 120
+
+uniform sampler2D DiffuseSampler;
+
+varying vec2 texCoord;
+
+uniform float InverseAmount;
+
+void main(){
+    vec4 diffuseColor = texture2D(DiffuseSampler, texCoord);
+    vec4 invertColor = 1.0 - diffuseColor;
+    vec4 outColor = mix(diffuseColor, invertColor, InverseAmount);
+    gl_FragColor = vec4(outColor.rgb, 1.0);
+}