TouchDesigner中通过GLSL 把视频变成六角形、三角形和圆形的像素化效果

做的几个类似的滤镜实验，主要是想把普通的视频做成能有一些比较风格化的效果，参考了shadertoys里面的一些案例，然后在touchdesigner中分别实现了六角形、三角形和圆形的马赛克效果，如果再做一些颜色调整其实能达到比较有意思的互动效果。下面是效果图：

original

hexagon

circle

triangle

当然所有效果也都是实时的。

下面是代码：

HEXAGON，这个效果在搜寻最近六边形上有一个大神已经把算法做好了，直接照着他的用就好了：

http://www.gamedev.net/page/resources/_/technical/game-programming/coordinates-in-hexagon-based-tile-maps-r1800

layout(location = 0) out vec4 fragColor;
uniform float size;
uniform float edge;
uniform float samples;

const float PI = 3.14159265359;
const float TAU = 2.0*PI;
const float deg30 = TAU/12.0;

vec4 resolution = uTD2DInfos[0].res;

float hexDist(vec2 a, vec2 b){
    vec2 p = abs(b-a);
    float s = sin(deg30);
    float c = cos(deg30);

    float diagDist = s*p.x + c*p.y;
    return max(diagDist, p.x)/c;
}

vec2 nearestHex(float s, vec2 st){
    float h = sin(deg30)*s;
    float r = cos(deg30)*s;
    float b = s + 2.0*h;
    float a = 2.0*r;
    float m = h/r;

    vec2 sect = st/vec2(2.0*r, h+s);
    vec2 sectPxl = mod(st, vec2(2.0*r, h+s));

    float aSection = mod(floor(sect.y), 2.0);

    vec2 coord = floor(sect);
    if(aSection > 0.0){
        if(sectPxl.y < (h-sectPxl.x*m)){
            coord -= 1.0;
        }
        else if(sectPxl.y < (-h + sectPxl.x*m)){
            coord.y -= 1.0;
        }

    }
    else{
        if(sectPxl.x > r){
            if(sectPxl.y < (2.0*h - sectPxl.x * m)){
                coord.y -= 1.0;
            }
        }
        else{
            if(sectPxl.y < (sectPxl.x*m)){
                coord.y -= 1.0;
            }
            else{
                coord.x -= 1.0;
            }
        }
    }

    float xoff = mod(coord.y, 2.0)*r;
    return vec2(coord.x*2.0*r-xoff, coord.y*(h+s))+vec2(r*2.0, s);
}

vec4 sampleColor(vec2 position){

    vec2 hor = vec2(0.002, 0.0);
    vec2 ver = vec2(0.0, 0.002);
    int count = 0;
    vec3 amountColor = vec3(0.0);

    for(int i = 1; i <= samples; i++){
        vec2 tmpHor = hor * i;
        vec2 tmpVer = ver * i;

        amountColor += texture(sTD2DInputs[0], position - tmpHor).rgb +
                      texture(sTD2DInputs[0], position + tmpHor).rgb +
                      texture(sTD2DInputs[0], position - tmpVer).rgb +
                      texture(sTD2DInputs[0], position + tmpVer).rgb;
        count++;
    }

    amountColor /= (float(count) * 4.0);
    return vec4(amountColor, 1.0);
}

void main(){
    vec4 videoColor = texture(sTD2DInputs[0], vUV.st);
    vec2 nearest = nearestHex(size, resolution.zw*vUV.st);
    vec4 sampleColor = sampleColor(nearest/resolution.zw);
    float dist = hexDist(vUV.st * resolution.zw, nearest);

    float interior = 1.0 - smoothstep(size - edge, size, dist);

    fragColor = vec4(sampleColor.rgb*interior, 1.0);

}

CIRCLE

layout(location = 0) out vec4 fragColor;
uniform float size;
uniform float samples;
uniform float board;

const float PI = 3.14159265359;
const float TAU = 2.0*PI;
const float deg30 = TAU/12.0;

vec4 resolution = uTD2DInfos[0].res;

int cutEdge(float dist, float size){
    int flag;
    if(dist <= (size - board)/2.0){flag = 1;}
    else{flag = 0;}
    return flag;
}

vec4 filterColor(vec2 position){
    vec2 hor = vec2(0.001, 0.0);
    vec2 ver = vec2(0.0, 0.001);
    int count = 0;
    vec3 amountColor = vec3(0.0);

    for(int i = 1; i <= samples; i++){
        vec2 tmpHor = hor * i;
        vec2 tmpVer = ver * i;

        amountColor += texture(sTD2DInputs[0], position - tmpHor).rgb +
                      texture(sTD2DInputs[0], position + tmpHor).rgb +
                      texture(sTD2DInputs[0], position - tmpVer).rgb +
                      texture(sTD2DInputs[0], position + tmpVer).rgb;
        count++;
    }

    amountColor /= (float(count) * 4.0);
    return vec4(amountColor, 1.0);
}

vec2 nearestCenter(float size, vec2 st){
    vec2 currentPos = st * resolution.zw;

    //find the unit
    vec2 unit = floor(currentPos / vec2(size));
    return unit * size + vec2(size/2.0);
}

void main(){
    vec4 videoColor = texture(sTD2DInputs[0], vUV.st);
    vec2 nearCenter = nearestCenter(size, vUV.st);
    vec4 sampleColor = filterColor(nearCenter / resolution.zw);

    float dist = distance(nearCenter, vUV.st * resolution.zw);

    int interior = cutEdge(dist, size);

    fragColor = vec4(sampleColor.rgb * interior, 1.0);
    //fragColor = vec4(vec3(interior), 1.0);
}

TRIANGLE

这一个效果直接是抄的一个大神的算法，妈的真是神了，简单一行就定义好了图像采样的方法，给大家看后反馈的结果还TM是最好的。真不知道这些神一样存在的人脑袋里面都装了一些什么.....

layout(location = 0) out vec4 fragColor;
uniform vec2 tile_num;

void main(){
    vec2 uv = vUV.st;
    vec2 uv2 = floor(uv*tile_num)/tile_num;
    uv -= uv2;
    uv *= tile_num;

    fragColor = texture(sTD2DInputs[0],
                        uv2 + vec2(step(1.0-uv.y,uv.x)/(2.0*tile_num.x),step(uv.x,uv.y)/(2.0*tile_num.y))
                        );

}