Update asciiart.glsl
This commit is contained in:
parent
d13e9c5aa8
commit
f59c7f25da
|
@ -26,7 +26,7 @@ void main()
|
||||||
vec4 mina = vec4(0.0, 0.0, 0.0, 0.0);
|
vec4 mina = vec4(0.0, 0.0, 0.0, 0.0);
|
||||||
vec4 minb = vec4(0.0, 0.0, 0.0, 0.0);
|
vec4 minb = vec4(0.0, 0.0, 0.0, 0.0);
|
||||||
|
|
||||||
for(int i=0; i<char_count; i++)
|
for (int i=0; i<char_count; i++)
|
||||||
{
|
{
|
||||||
vec4 ff = vec4(0.0, 0.0, 0.0, 0.0);
|
vec4 ff = vec4(0.0, 0.0, 0.0, 0.0);
|
||||||
vec4 f = vec4(0.0, 0.0, 0.0, 0.0);
|
vec4 f = vec4(0.0, 0.0, 0.0, 0.0);
|
||||||
|
@ -34,9 +34,9 @@ void main()
|
||||||
vec4 t = vec4(0.0, 0.0, 0.0, 0.0);
|
vec4 t = vec4(0.0, 0.0, 0.0, 0.0);
|
||||||
vec4 tt = vec4(0.0, 0.0, 0.0, 0.0);
|
vec4 tt = vec4(0.0, 0.0, 0.0, 0.0);
|
||||||
|
|
||||||
for(int x=0; x<char_width; x++)
|
for (int x=0; x<char_width; x++)
|
||||||
{
|
{
|
||||||
for(int y=0; y<char_height; y++)
|
for (int y=0; y<char_height; y++)
|
||||||
{
|
{
|
||||||
vec2 tex_pos = char_pos*char_dim + vec2(x,y) + 0.5;
|
vec2 tex_pos = char_pos*char_dim + vec2(x,y) + 0.5;
|
||||||
vec4 tex = texture(samp9, tex_pos * resolution.zw);
|
vec4 tex = texture(samp9, tex_pos * resolution.zw);
|
||||||
|
@ -53,39 +53,38 @@ void main()
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
/*
|
// The next lines are a bit harder, hf :-)
|
||||||
The next lines are a bit harder, hf :-)
|
|
||||||
|
|
||||||
The idea is to find the perfect char with the perfect background color and the perfect font color.
|
// The idea is to find the perfect char with the perfect background color and the perfect font color.
|
||||||
As this is an equation with three unknowns, we can't just try all chars and color combinations.
|
// As this is an equation with three unknowns, we can't just try all chars and color combinations.
|
||||||
|
|
||||||
As criterion how "perfect" the selection is, we compare the "mean squared error" of the resulted colors of all chars.
|
// As criterion how "perfect" the selection is, we compare the "mean squared error" of the resulted colors of all chars.
|
||||||
So, now the big issue: how to calculate the MSE without knowing the two colors ...
|
// So, now the big issue: how to calculate the MSE without knowing the two colors ...
|
||||||
|
|
||||||
In the next steps, "a" is the font color, "b" is the background color, "f" is the font value at this pixel, "t" is the texture value
|
// In the next steps, "a" is the font color, "b" is the background color, "f" is the font value at this pixel, "t" is the texture value
|
||||||
|
|
||||||
So the square error of one pixel is:
|
// So the square error of one pixel is:
|
||||||
e = ( t - a⋅f - b⋅(1-f) ) ^ 2
|
// e = ( t - a⋅f - b⋅(1-f) ) ^ 2
|
||||||
|
|
||||||
In longer:
|
// In longer:
|
||||||
e = a^2⋅f^2 - 2⋅a⋅b⋅f^2 + 2⋅a⋅b⋅f - 2⋅a⋅f⋅t + b^2⋅f^2 - 2⋅b^2⋅f + b^2 + 2⋅b⋅f⋅t - 2⋅b⋅t + t^2
|
// e = a^2⋅f^2 - 2⋅a⋅b⋅f^2 + 2⋅a⋅b⋅f - 2⋅a⋅f⋅t + b^2⋅f^2 - 2⋅b^2⋅f + b^2 + 2⋅b⋅f⋅t - 2⋅b⋅t + t^2
|
||||||
|
|
||||||
The sum of all errors is: (as shortcut, ff,f,ft,t,tt are now the sums like declared above, sum(1) is the count of pixels)
|
// The sum of all errors is: (as shortcut, ff,f,ft,t,tt are now the sums like declared above, sum(1) is the count of pixels)
|
||||||
sum(e) = a^2⋅ff - 2⋅a^2⋅ff + 2⋅a⋅b⋅f - 2⋅a⋅ft + b^2⋅ff - 2⋅b^2⋅f + b^2⋅sum(1) + 2⋅b⋅ft - 2⋅b⋅t + tt
|
// sum(e) = a^2⋅ff - 2⋅a^2⋅ff + 2⋅a⋅b⋅f - 2⋅a⋅ft + b^2⋅ff - 2⋅b^2⋅f + b^2⋅sum(1) + 2⋅b⋅ft - 2⋅b⋅t + tt
|
||||||
|
|
||||||
To find the minimum, we have to derive this by "a" and "b":
|
// To find the minimum, we have to derive this by "a" and "b":
|
||||||
d/da sum(e) = 2⋅a⋅ff + 2⋅b⋅f - 2⋅b⋅ff - 2⋅ft
|
// d/da sum(e) = 2⋅a⋅ff + 2⋅b⋅f - 2⋅b⋅ff - 2⋅ft
|
||||||
d/db sum(e) = 2⋅a⋅f - 2⋅a⋅ff - 4⋅b⋅f + 2⋅b⋅ff + 2⋅b⋅sum(1) + 2⋅ft - 2⋅t
|
// d/db sum(e) = 2⋅a⋅f - 2⋅a⋅ff - 4⋅b⋅f + 2⋅b⋅ff + 2⋅b⋅sum(1) + 2⋅ft - 2⋅t
|
||||||
|
|
||||||
|
// So, both equations must be zero at minimum and there is only one solution.
|
||||||
|
|
||||||
So, both equations must be zero at minimum and there is only one solution.
|
|
||||||
*/
|
|
||||||
vec4 a = (f*ft - ff*t + f*t - ft*float(char_pixels)) / (f*f - ff*float(char_pixels));
|
vec4 a = (f*ft - ff*t + f*t - ft*float(char_pixels)) / (f*f - ff*float(char_pixels));
|
||||||
vec4 b = (f*ft - ff*t) / (f*f - ff*float(char_pixels));
|
vec4 b = (f*ft - ff*t) / (f*f - ff*float(char_pixels));
|
||||||
|
|
||||||
vec4 diff = a*a*ff + 2.0*a*b*f - 2.0*a*b*ff - 2.0*a*ft + b*b *(-2.0*f + ff + float(char_pixels)) + 2.0*b*ft - 2.0*b*t + tt;
|
vec4 diff = a*a*ff + 2.0*a*b*f - 2.0*a*b*ff - 2.0*a*ft + b*b *(-2.0*f + ff + float(char_pixels)) + 2.0*b*ft - 2.0*b*t + tt;
|
||||||
float diff_f = dot(diff, vec4(1.0, 1.0, 1.0, 1.0));
|
float diff_f = dot(diff, vec4(1.0, 1.0, 1.0, 1.0));
|
||||||
|
|
||||||
if(diff_f < mindiff) {
|
if (diff_f < mindiff) {
|
||||||
mindiff = diff_f;
|
mindiff = diff_f;
|
||||||
minc = float(i);
|
minc = float(i);
|
||||||
mina = a;
|
mina = a;
|
||||||
|
|
Loading…
Reference in New Issue