refactor(default): add demo logo on main screen

default/frag9.glsl

@@ -7,12 +7,17 @@ in vec2 vUV;
 out vec4 fragColor;
 
 #include inc_map.glsl
+#include inc_cp437.glsl
 
 uniform sampler2D iTex0;
 uniform vec3 iGroup2_4[7];
 uniform vec3 iGroup2_5[7];
 uniform vec3 iGroup2_6[7];
 uniform vec3 iGroup2_7[7];
+uniform int iFPS;
+uniform int iDemo;
+
+const int[] textDEMO = int[5](0x44, 0x45, 0x4D, 0x4F, 0x00);
 
 void main() {
     bool visible = (iGroup2_4[4].x + iGroup2_5[4].x + iGroup2_6[4].x + iGroup2_7[4].x) > 0;
@@ -104,6 +109,9 @@ void main() {
 
     vec4 color = texture(iTex0, invert ? vUV : uv);
 
+    color = mix(color, 1. - color, iDemo * write_int(uv * 20., vec2(1.), iFPS, 2));
+    color = mix(color, 1. - color, iDemo * write_5(uv * 20., vec2(1., 18.), textDEMO));
+
     if (visible) {
         float mask = step(0.0001, length(uv));
         color *= mix(mask, 1 - mask, invert ? 1 : 0);