Add generic 1D texture map pass

shaders/glava/util/pass.frag

@@ -0,0 +1,9 @@
+uniform sampler1D tex;
+
+out vec4 fragment;
+in vec4 gl_FragCoord;
+
+/* 1D texture mapping */
+void main() {
+    fragment.r = texelFetch(tex, int(gl_FragCoord.x), 0).r;
+}