drawRainBow：整理代码，移除冗余变量

demo/2d/Creator3.8.0_2D_DrawRainbow/assets/main.scene

@@ -1,7 +1,7 @@
 [
   {
     "__type__": "cc.SceneAsset",
-    "_name": "rainbow",
+    "_name": "main",
     "_objFlags": 0,
     "__editorExtras__": {},
     "_native": "",
@@ -11,7 +11,7 @@
   },
   {
     "__type__": "cc.Scene",
-    "_name": "rainbow",
+    "_name": "main",
     "_objFlags": 0,
     "__editorExtras__": {},
     "_parent": null,
@@ -175,7 +175,7 @@
     "_priority": 1073741824,
     "_fov": 45,
     "_fovAxis": 0,
-    "_orthoHeight": 320,
+    "_orthoHeight": 414.62365591397844,
     "_near": 1,
     "_far": 2000,
     "_color": {

demo/2d/Creator3.8.0_2D_DrawRainbow/assets/res/rainbow.effect

@@ -32,10 +32,6 @@ CCProgram sprite-vs %{
   out vec4 v_color;
   out vec2 v_uv0;
 
-  #if USE_TEXTURE
-    in vec2 a_uv0;
-  #endif
-
   vec4 vert () {
     vec4 pos = vec4(a_position, 1);
 
@@ -51,10 +47,6 @@ CCProgram sprite-vs %{
       pos = cc_matViewProj * pos;
     #endif
 
-    #if USE_TEXTURE
-      v_uv0 = a_uv0;
-    #endif
-
     v_color = a_color;
     v_uv0 = a_texCoord;
 
@@ -91,7 +83,6 @@ CCProgram sprite-fs %{
 
   vec4 frag() {
     vec3 color = vec3(1,1,1);
-    // vec2 point = vec2(.5,1.);
     vec2 point = vec2(.5,.5);
 
     float circleline_red = drawHalfCircleLine(point, v_uv0, .4, .05);
@@ -121,10 +112,7 @@ CCProgram sprite-fs %{
     // vec3 c = vec3(0.);
     // float x = v_uv0.x;
     // float y = v_uv0.y;
-    // c = vec3(sin(4.*x+0.85)*2.-0.5,
-    //             sin(5.*x-1.),
-    //             sin(3.*x-1.5) *1.5
-    //             );
+    // c = vec3(sin(4.*x+0.85)*2.-0.5, sin(5.*x-1.),sin(3.*x-1.5) *1.5);
     // o = vec4(c, 1);
     
     return o;