fix(default): small fixes in default project

default/frag9.glsl

@@ -109,7 +109,7 @@ 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_int_left(uv * 20., vec2(1., 1.), iFPS, 3));
     color = mix(color, 1. - color, iDemo * write_5(uv * 20., vec2(1., 18.), textDEMO));
 
     if (visible) {

default/inc_cp437.glsl

@@ -381,6 +381,7 @@ float write_int_left(vec2 uv, vec2 pos, int value, int magnitude)
     int i;
     int m = 1;
     float d = 0.;
+    pos.x -= magnitude;
     for (i = 0; i < magnitude; i++) {
         if (i == 0 || value >= m) {
             pos.x += 1.;

default/inc_debug.glsl

@@ -222,7 +222,7 @@ vec4 debug(vec2 vUV)
 
     // show mix
     f += char_at(uv2, vec2(1.55, -.6), mix_type ? 0x4B : 0x4D);
-    f = mix(f, 1 - f, rect(uv2, vec2(.2, -.9 + .9 * mix_value), vec2(.9, .9 * mix_value)));
+    f = mix(f, 1 - f, rect(uv2, vec2(2., -.9 + .9 * mix_value), vec2(.9, .9 * mix_value)));
 
     // show debug info
     float v = 0.;

default/inc_rand.glsl

@@ -1,14 +1,20 @@
 #ifndef INC_RAND
 #define INC_RAND
 
+// https://thebookofshaders.com/10/
+// https://byteblacksmith.com/improvements-to-the-canonical-one-liner-glsl-rand-for-opengl-es-2-0/
+
 float rand(float seed){
-    float v = pow(abs(seed), .8571429); // 6. / 7.
-    v *= sin(v) + 1.;
-    return fract(v);
+    const float c =  43758.5453;
+    return fract(sin(seed) * c);
 }
 
-float rand(vec2 n){
-    return rand(n.x * 1234. + n.y * 9876.);
+float rand(vec2 co)
+{
+    const float a = 12.9898;
+    const float b = 78.233;
+    float dt= dot(co.xy ,vec2(a,b));
+    return rand(dt);
 }
 
 #endif