refactor(glsl): rename uniforms as iXxx

shaders/frag4.glsl

@@ -5,8 +5,8 @@
 in vec2 vUV;
 out vec4 fragColor;
 
-uniform vec3 src1_2[6];
+uniform vec3 iMidi1_2[6];
 
 void main() {
-    fragColor = src_stage(vUV, seed4, src1_2[0], src1_2[1].xy, src1_2[2], src1_2[3].xy, src1_2[4], src1_2[5].xy);
+    fragColor = src_stage(vUV, iSeed4, iMidi1_2[0], iMidi1_2[1].xy, iMidi1_2[2], iMidi1_2[3].xy, iMidi1_2[4], iMidi1_2[5].xy);
 }