Added shaders examples resources

examples/resources/shaders/grayscale.fs

@@ -1,15 +1,20 @@
-#version 110
+#version 330
+
+in vec2 fragTexCoord;
+
+out vec4 fragColor;
 
 uniform sampler2D texture0;
-varying vec2 fragTexCoord;
-varying vec4 fragColor;
+uniform vec4 tintColor;
+
+// NOTE: Add here your custom variables
 
 void main()
 {
-    vec4 base = texture2D(texture0, fragTexCoord)*fragColor;
-
+    vec4 base = texture2D(texture0, fragTexCoord)*tintColor;
+    
     // Convert to grayscale using NTSC conversion weights
     float gray = dot(base.rgb, vec3(0.299, 0.587, 0.114));
     
-    gl_FragColor = vec4(gray, gray, gray, base.a);
+    fragColor = vec4(gray, gray, gray, tintColor.a);
 }