I am trying to pass an array of vec3 as uniform and then iterate through them on each pixel. The size of array varies on situations so I can't make the loop with constant number of iterations.
Here is the code:
precision highp float;
precision highp int;
varying vec4 v_fragmentColor;
varying vec4 v_pos;
uniform int u_numberOfParticles;
const int numberOfAccumsToCapture = 3;
const float threshold = 0.15;
const float gooCoeff = 1.19;
uniform mat4 u_MVPMatrix;
uniform vec3 u_waterVertices[100];
void main()
{
vec4 finalColor = vec4(0.0, 0.0, 0.0, 0.0);
vec2 currPos = v_pos.xy;
float accum = 0.0;
vec3 normal = vec3(0, 0, 0);
for ( int i = 0; i < u_numberOfParticles; ++i )
{
vec2 dir2 = u_waterVertices[i].xy - currPos.xy;
vec3 dir3 = vec3(dir2, 0.1);
float q = dot(dir2, dir2);
accum += u_waterVertices[i].z / q;
}
float normalizeToEdge = 1.0 - (accum - threshold) / 2.0;
if (normalizeToEdge < 0.4)
finalColor = vec4( 0.1, normalizeToEdge + 0.5, 0.9-normalizeToEdge*0.4, 1.0);
if ( normalizeToEdge < 0.2 )
{
finalColor = vec4( 120.0/255.0, 245.0/255.0, 245.0/255.0, 1.0);
float shade = mix( 0.7, 1.0, normal.x);
finalColor *= shade;
}
gl_FragColor = vec4(finalColor);
}
The problem is here:
for ( int i = 0; i < u_numberOfParticles; ++i )
{
vec2 dir2 = u_waterVertices[i].xy - currPos.xy;
vec3 dir3 = vec3(dir2, 0.1);
float q = dot(dir2, dir2);
accum += u_waterVertices[i].z / q;
}
When I make the for-loop like this
for ( int i = 0; i < 2; ++i )
{
//...
}
I get double the framerate even though u_numberOfParticles is also 2
Making it like this
for ( int i = 0; i < 100; ++i )
{
if (i == u_numberOfParticles)
break;
//...
}
gives no improvement.
The only way I know to cope with this situation is to create multiple shaders. But The size of array may vary from 1 to 40 and making 40 different shaders just because of the for-loop is stupid. Any help or ideas how to deal with this situation ?
