neercs: fix background colour computations with shader model 3.

neercs/video/text.lolfx

@@ -45,12 +45,12 @@ void main()
 #else
     vec4 tmp_Attr = in_Attr * 255.0;
 
-    float A = 0.0;
-    float B = 0.0;
-    float C = 0.0;
-    float D = 0.0;
+    float A = floor(tmp_Attr.w / 32.0) / 7.0;
+    float B = mod(floor(tmp_Attr.w / 2.0), 16.0) / 15.0;
+    float C = (mod(tmp_Attr.w, 2.0) * 8.0 + floor(tmp_Attr.z / 32.0)) / 15.0;
+    float D = mod(floor(tmp_Attr.z / 4.0), 8.0) / 7.0;
 
-    float E = 0.0;
+    float E = (mod(tmp_Attr.z, 4.0) * 2.0 + floor(tmp_Attr.y / 128.0)) / 7.0;
     float F = mod(floor(tmp_Attr.y / 8.0), 16.0) / 15.0;
     float G = (mod(tmp_Attr.y, 8.0) * 2.0 + floor(tmp_Attr.x / 128.0)) / 15.0;
     float H = mod(floor(tmp_Attr.x / 16.0), 8.0) / 7.0;