Edrem - Luminance Grayscale

// Grayscale shader by daxnitro.
// Small edit by Edrem
// It makes the green brighter =D

uniform sampler2D sampler0;
uniform sampler2D sampler1;
uniform sampler2D sampler2;

uniform float near;
uniform float far;

float getBrightness(vec4 color);
float getDepth(vec2 coord);

void applyEffect() {
    float brightness = getBrightness(gl_FragColor);
    gl_FragColor = vec4(brightness, brightness, brightness, gl_FragColor[3]);
}

void main() {
    vec4 baseColor = texture2D(sampler0, gl_TexCoord[0].st);

    gl_FragColor = baseColor;

    float depth = getDepth(gl_TexCoord[0].st);

    if (gl_FragColor[3] == 0.0) {
        gl_FragColor = gl_Fog.color;
    }

    applyEffect();
}

float getBrightness(vec4 color) {
    return color[0] * 0.299f + color[1] * 0.587f + color[2] * 0.114f;
}

float getDepth(vec2 coord) {
    float depth = texture2D(sampler1, coord).x;
    float depth2 = texture2D(sampler2, coord).x;
    if (depth2 < 1.0) {
        depth = depth2;
    }

    depth = 2.0 * near * far / (far + near - (2.0 * depth - 1.0) * (far - near));

    return depth;
}