// Vertex
varying vec2 vertTexCoord;

attribute vec3 in_Position;
attribute vec2 in_TextureCoord;

void main() {
    vertTexCoord = in_TextureCoord;
    gl_Position = gm_Matrices[MATRIX_WORLD_VIEW_PROJECTION] * vec4(in_Position, 1.0);
}

// Fragment
uniform sampler2D depthMap;
uniform vec2 screenSize;
uniform float blurSize;
uniform float depth;
uniform float range;
uniform float fadeSize;
uniform float zfar;

varying vec2 vertTexCoord;

const float pi = 3.14159265;
const float tau = pi * 2.0;
const int samples = 15;
const int ringDetail = 4;
const int totalSamples = samples * ringDetail;

float screenSampleSize = screenSize.y * blurSize;
vec2 texelSize = 1.0 / screenSize;

float colorToFloat(vec3 c) { return c.r + c.g / 255.0 + c.b / (255.0 * 255.0); }
float getDepth(vec2 coord) { return colorToFloat(texture2D(depthMap, coord).rgb) * zfar; }
float getBlur(float d) { return clamp((abs(d - depth) - range) / fadeSize, 0.0, 1.0); }
float getFrontBlur(float d) { return clamp(((depth - range) - d) / fadeSize, 0.0, 1.0); }
float getBackBlur(float d) { return clamp((d - (depth + range)) / fadeSize, 0.0, 1.0); }

void main() {
    float myDepth = getDepth(vertTexCoord), myFrontBlur = getFrontBlur(myDepth), myBackBlur = getBackBlur(myDepth);
    float blur = 0.0, maxdis = screenSampleSize * screenSampleSize + screenSampleSize * screenSampleSize, colorDiv = 0.0;
    vec4 colorAdd = vec4(0.0);
    gl_FragColor = texture2D(gm_BaseTexture, vertTexCoord);

    for (int i = 0; i < totalSamples; i++) {
        float angle = (float(i / ringDetail) / float(samples)) * tau;
        float dis = 1.0 - mod(float(i),float(ringDetail)) / float(ringDetail);
        vec2 offset = vec2(cos(angle), sin(angle)) * dis * screenSampleSize;
        vec2 tex = vertTexCoord + texelSize * offset;
        float sampleDepth = getDepth(tex);
        float sampleBlur = getBlur(sampleDepth);
        float mul = dis * (1.0 - (1.0 - sampleBlur) * myBackBlur);
        if (mul > 0.0) {
            colorAdd += texture2D(gm_BaseTexture, tex) * mul;
            colorDiv += mul;
        }
        blur += getFrontBlur(sampleDepth);
    }
    blur /= float(totalSamples);
    blur += myFrontBlur + myBackBlur;
    colorAdd *= blur;
    colorDiv *= blur;
    gl_FragColor += colorAdd;
    gl_FragColor /= colorDiv + 1.0;
}