bsp.fs.glsl

#version 430

precision highp float;
precision highp sampler2D;

uniform sampler2D uBSPTree;
uniform sampler2D uSDF;
uniform vec4 uBGColor;
uniform vec4 uFGColor;

in vec2 vTexCoord;

out vec4 oFragCoord;

void main() {
    vec4 data;
    int node = 0;
    while ((data = texelFetch(uBSPTree, ivec2(0, node), 0)).w < 1.0) {
        float value = data.w == 0.0 ? vTexCoord.x : vTexCoord.y;
        node = int(data.x <= value ? data.y : data.z);
    }
    vec4 srcRect = texelFetch(uBSPTree, ivec2(1, node), 0);
    vec4 uvRect = texelFetch(uBSPTree, ivec2(2, node), 0);
    vec2 uv = mix((vTexCoord - srcRect.xy) / (srcRect.zw - srcRect.xy), uvRect.xy, uvRect.zw);
    vec4 texel = texture(uSDF, uv);
    float alpha = texel.b == 0.0 ? min(texel.r, texel.g) : max(texel.r, texel.g);
    oFragCoord = mix(uBGColor, uFGColor, alpha);
}