Kelsidavis-WoWee/assets/shaders/wmo.frag.glsl

#version 450

layout(set = 0, binding = 0) uniform PerFrame {
    mat4 view;
    mat4 projection;
    mat4 lightSpaceMatrix;
    vec4 lightDir;
    vec4 lightColor;
    vec4 ambientColor;
    vec4 viewPos;
    vec4 fogColor;
    vec4 fogParams;
    vec4 shadowParams;
};

layout(set = 1, binding = 0) uniform sampler2D uTexture;

layout(set = 1, binding = 1) uniform WMOMaterial {
    int hasTexture;
    int alphaTest;
    int unlit;
    int isInterior;
    float specularIntensity;
    int isWindow;
    int enableNormalMap;
    int enablePOM;
    float pomScale;
    int pomMaxSamples;
    float heightMapVariance;
};

layout(set = 1, binding = 2) uniform sampler2D uNormalHeightMap;

layout(set = 0, binding = 1) uniform sampler2DShadow uShadowMap;

layout(location = 0) in vec3 FragPos;
layout(location = 1) in vec3 Normal;
layout(location = 2) in vec2 TexCoord;
layout(location = 3) in vec4 VertColor;
layout(location = 4) in vec3 Tangent;
layout(location = 5) in vec3 Bitangent;

layout(location = 0) out vec4 outColor;

// LOD factor from screen-space UV derivatives
float computeLodFactor() {
    vec2 dx = dFdx(TexCoord);
    vec2 dy = dFdy(TexCoord);
    float texelDensity = max(dot(dx, dx), dot(dy, dy));
    // Low density = close/head-on = full detail (0)
    // High density = far/steep = vertex normals only (1)
    return smoothstep(0.0001, 0.005, texelDensity);
}

// Parallax Occlusion Mapping with angle-adaptive sampling
vec2 parallaxOcclusionMap(vec2 uv, vec3 viewDirTS, float lodFactor) {
    float VdotN = abs(viewDirTS.z);  // 1=head-on, 0=grazing
    float angleFactor = clamp(VdotN, 0.15, 1.0);
    int maxS = pomMaxSamples;
    int minS = max(maxS / 4, 4);
    int numSamples = int(mix(float(minS), float(maxS), angleFactor));
    numSamples = int(mix(float(minS), float(numSamples), 1.0 - lodFactor));

    float layerDepth = 1.0 / float(numSamples);
    float currentLayerDepth = 0.0;

    // Direction to shift UV per layer
    vec2 P = viewDirTS.xy / max(abs(viewDirTS.z), 0.001) * pomScale;
    vec2 deltaUV = P / float(numSamples);

    vec2 currentUV = uv;
    float currentDepthMapValue = 1.0 - texture(uNormalHeightMap, currentUV).a;

    // Ray march through layers
    for (int i = 0; i < 64; i++) {
        if (i >= numSamples || currentLayerDepth >= currentDepthMapValue) break;
        currentUV -= deltaUV;
        currentDepthMapValue = 1.0 - texture(uNormalHeightMap, currentUV).a;
        currentLayerDepth += layerDepth;
    }

    // Interpolate between last two layers for smooth result
    vec2 prevUV = currentUV + deltaUV;
    float afterDepth = currentDepthMapValue - currentLayerDepth;
    float beforeDepth = (1.0 - texture(uNormalHeightMap, prevUV).a) - currentLayerDepth + layerDepth;
    float weight = afterDepth / (afterDepth - beforeDepth + 0.0001);
    return mix(currentUV, prevUV, weight);
}

void main() {
    float lodFactor = computeLodFactor();

    vec3 vertexNormal = normalize(Normal);
    if (!gl_FrontFacing) vertexNormal = -vertexNormal;

    // Compute final UV (with POM if enabled)
    vec2 finalUV = TexCoord;

    // Build TBN matrix
    vec3 T = normalize(Tangent);
    vec3 B = normalize(Bitangent);
    vec3 N = vertexNormal;
    mat3 TBN = mat3(T, B, N);

    if (enablePOM != 0 && heightMapVariance > 0.001 && lodFactor < 0.99) {
        mat3 TBN_inv = transpose(TBN);
        vec3 viewDirWorld = normalize(viewPos.xyz - FragPos);
        vec3 viewDirTS = TBN_inv * viewDirWorld;
        finalUV = parallaxOcclusionMap(TexCoord, viewDirTS, lodFactor);
    }

    vec4 texColor = hasTexture != 0 ? texture(uTexture, finalUV) : vec4(1.0);
    if (alphaTest != 0 && texColor.a < 0.5) discard;

    // Compute normal (with normal mapping if enabled)
    vec3 norm = vertexNormal;
    if (enableNormalMap != 0 && lodFactor < 0.99) {
        vec3 mapNormal = texture(uNormalHeightMap, finalUV).rgb * 2.0 - 1.0;
        vec3 worldNormal = normalize(TBN * mapNormal);
        if (!gl_FrontFacing) worldNormal = -worldNormal;
        norm = normalize(mix(worldNormal, vertexNormal, lodFactor));
    }

    vec3 result;

    if (unlit != 0) {
        result = texColor.rgb;
    } else if (isInterior != 0) {
        vec3 mocv = max(VertColor.rgb, vec3(0.5));
        result = texColor.rgb * mocv;
    } else {
        vec3 ldir = normalize(-lightDir.xyz);
        float diff = max(dot(norm, ldir), 0.0);

        vec3 viewDir = normalize(viewPos.xyz - FragPos);
        vec3 halfDir = normalize(ldir + viewDir);
        float spec = pow(max(dot(norm, halfDir), 0.0), 32.0) * specularIntensity;

        float shadow = 1.0;
        if (shadowParams.x > 0.5) {
            vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
            vec3 proj = lsPos.xyz / lsPos.w;
            proj.xy = proj.xy * 0.5 + 0.5;
            if (proj.x >= 0.0 && proj.x <= 1.0 &&
                proj.y >= 0.0 && proj.y <= 1.0 &&
                proj.z >= 0.0 && proj.z <= 1.0) {
                float bias = max(0.0005 * (1.0 - dot(norm, ldir)), 0.00005);
                shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
            }
            shadow = mix(1.0, shadow, shadowParams.y);
        }

        result = ambientColor.rgb * texColor.rgb
               + shadow * (diff * lightColor.rgb * texColor.rgb + spec * lightColor.rgb);

        result *= max(VertColor.rgb, vec3(0.5));
    }

    float dist = length(viewPos.xyz - FragPos);
    float fogFactor = clamp((fogParams.y - dist) / (fogParams.y - fogParams.x), 0.0, 1.0);
    result = mix(fogColor.rgb, result, fogFactor);

    float alpha = texColor.a;

    // Window glass: opaque but simulates dark tinted glass with reflections.
    if (isWindow != 0) {
        vec3 viewDir = normalize(viewPos.xyz - FragPos);
        float NdotV = abs(dot(norm, viewDir));
        float fresnel = 0.08 + 0.92 * pow(1.0 - NdotV, 4.0);

        vec3 ldir = normalize(-lightDir.xyz);
        vec3 reflectDir = reflect(-viewDir, norm);
        float sunGlint = pow(max(dot(reflectDir, ldir), 0.0), 32.0);

        float baseBrightness = mix(0.3, 0.9, sunGlint);
        vec3 glass = result * baseBrightness;

        vec3 reflectTint = mix(ambientColor.rgb * 1.2, vec3(0.6, 0.75, 1.0), 0.6);
        glass = mix(glass, reflectTint, fresnel * 0.8);

        vec3 halfDir = normalize(ldir + viewDir);
        float spec = pow(max(dot(norm, halfDir), 0.0), 256.0);
        glass += spec * lightColor.rgb * 0.8;

        float specBroad = pow(max(dot(norm, halfDir), 0.0), 12.0);
        glass += specBroad * lightColor.rgb * 0.12;

        result = glass;
        alpha = mix(0.4, 0.95, NdotV);
    }

    outColor = vec4(result, alpha);
}