#version 150
precision highp float;

uniform sampler2DRect tex0; // Your FBO texture (RGB FBO)
uniform float texW; // FBO texture width
uniform float texH; // FBO texture height

out vec4 fragColor; // Output color
in vec2 varyingtexcoord;

void main() {
    float threshold = 0.7;
    float depth = texture(tex0, varyingtexcoord).r;

    // Determine which quadrant we're in
    int quadrantX = int(varyingtexcoord.x / (256.0 / 2.0));
    int quadrantY = int(varyingtexcoord.y / (336.0 / 2.0));
    int quadrant = quadrantY * 2 + quadrantX;

    vec3 baseColor;
    vec3 mixColor = vec3(0.0); // White for mixing in all quadrants

    // Choose base color based on quadrant
    if (quadrant == 0) {
        baseColor = vec3(1.0, 0.0, 0.0); // Red for bottom-left
    } else if (quadrant == 1) {
        baseColor = vec3(0.0, 1.0, 0.0); // Green for bottom-right
    } else if (quadrant == 2) {
        baseColor = vec3(0.0, 0.0, 1.0); // Blue for top-left
    } else {
        baseColor = vec3(1.0, 1.0, 1.0); // White for top-right
    }

    // Mix the base color with white based on the depth
    vec3 color = mix(mixColor, baseColor, depth);

    fragColor = vec4(color, 1.0);
}