uniform mat4 u_matrix;
uniform vec3 u_lightcolor;
uniform lowp vec3 u_lightpos;
uniform lowp float u_lightintensity;
uniform float u_vertical_gradient;
uniform lowp float u_opacity;
uniform float u_edge_radius;

attribute vec4 a_pos_normal_ed;
attribute vec2 a_centroid_pos;

#ifdef PROJECTION_GLOBE_VIEW
attribute vec3 a_pos_3;         // Projected position on the globe
attribute vec3 a_pos_normal_3;  // Surface normal at the position

uniform mat4 u_inv_rot_matrix;
uniform vec2 u_merc_center;
uniform vec3 u_tile_id;
uniform float u_zoom_transition;
uniform vec3 u_up_dir;
uniform float u_height_lift;
#endif

varying vec4 v_color;

#ifdef RENDER_SHADOWS
uniform mat4 u_light_matrix_0;
uniform mat4 u_light_matrix_1;

varying highp vec4 v_pos_light_view_0;
varying highp vec4 v_pos_light_view_1;
varying float v_depth;
#endif

#ifdef ZERO_ROOF_RADIUS
varying vec4 v_roof_color;
#endif

#if defined(ZERO_ROOF_RADIUS) || defined(RENDER_SHADOWS)
varying highp vec3 v_normal;
#endif

#ifdef FAUX_AO
uniform lowp vec2 u_ao;
varying vec3 v_ao;
#endif

#pragma mapbox: define highp float base
#pragma mapbox: define highp float height

#pragma mapbox: define highp vec4 color

void main() {
    #pragma mapbox: initialize highp float base
    #pragma mapbox: initialize highp float height
    #pragma mapbox: initialize highp vec4 color

    vec4 pos_nx = floor(a_pos_normal_ed * 0.5);
    // The least significant bits of a_pos_normal_ed hold:
    // x is 1 if it's on top, 0 for ground.
    // y is 1 if the normal points up, and 0 if it points to side.
    // z is sign of ny: 1 for positive, 0 for values <= 0.
    // w marks edge's start, 0 is for edge end, edgeDistance increases from start to end.
    vec4 top_up_ny_start = a_pos_normal_ed - 2.0 * pos_nx;
    vec3 top_up_ny = top_up_ny_start.xyz;

    float x_normal = pos_nx.z / 8192.0;
    vec3 normal = top_up_ny.y == 1.0 ? vec3(0.0, 0.0, 1.0) : normalize(vec3(x_normal, (2.0 * top_up_ny.z - 1.0) * (1.0 - abs(x_normal)), 0.0));
#if defined(ZERO_ROOF_RADIUS) || defined(RENDER_SHADOWS)
    v_normal = normal;
#endif

    base = max(0.0, base);

    height = max(0.0, top_up_ny.y == 0.0 && top_up_ny.x == 1.0 ? height - u_edge_radius : height);

    float t = top_up_ny.x;

    vec2 centroid_pos = vec2(0.0);
#if defined(HAS_CENTROID) || defined(TERRAIN)
    centroid_pos = a_centroid_pos;
#endif

    float ele = 0.0;
    float h = 0.0;
    float c_ele;
    vec3 pos;
#ifdef TERRAIN
    bool flat_roof = centroid_pos.x != 0.0 && t > 0.0;
    ele = elevation(pos_nx.xy);
    c_ele = flat_roof ? centroid_pos.y == 0.0 ? elevationFromUint16(centroid_pos.x) : flatElevation(centroid_pos) : ele;
    // If centroid elevation lower than vertex elevation, roof at least 2 meters height above base.
    h = flat_roof ? max(c_ele + height, ele + base + 2.0) : ele + (t > 0.0 ? height : base == 0.0 ? -5.0 : base);
    pos = vec3(pos_nx.xy, h);
#else
    h = t > 0.0 ? height : base;
    pos = vec3(pos_nx.xy, h);
#endif

#ifdef PROJECTION_GLOBE_VIEW
    // If t > 0 (top) we always add the lift, otherwise (ground) we only add it if base height is > 0
    float lift = float((t + base) > 0.0) * u_height_lift;
    h += lift;
    vec3 globe_normal = normalize(mix(a_pos_normal_3 / 16384.0, u_up_dir, u_zoom_transition));
    vec3 globe_pos = a_pos_3 + globe_normal * (u_tile_up_scale * h);
    vec3 merc_pos = mercator_tile_position(u_inv_rot_matrix, pos.xy, u_tile_id, u_merc_center) + u_up_dir * u_tile_up_scale * pos.z;
    pos = mix_globe_mercator(globe_pos, merc_pos, u_zoom_transition);
#endif

    float hidden = float(centroid_pos.x == 0.0 && centroid_pos.y == 1.0);
    gl_Position = mix(u_matrix * vec4(pos, 1), AWAY, hidden);

#ifdef RENDER_SHADOWS
    v_pos_light_view_0 = u_light_matrix_0 * vec4(pos, 1);
    v_pos_light_view_1 = u_light_matrix_1 * vec4(pos, 1);
    v_depth = gl_Position.w;
#endif

    float NdotL = 0.0;
    float colorvalue = 0.0;
#ifdef LIGHTING_3D_MODE
    NdotL = calculate_NdotL(normal);
#else
    // Relative luminance (how dark/bright is the surface color?)
    colorvalue = color.r * 0.2126 + color.g * 0.7152 + color.b * 0.0722;

    // Add slight ambient lighting so no extrusions are totally black
    vec4 ambientlight = vec4(0.03, 0.03, 0.03, 1.0);
    color += ambientlight;

    // Calculate cos(theta), where theta is the angle between surface normal and diffuse light ray
    NdotL = clamp(dot(normal, u_lightpos), 0.0, 1.0);

    // Adjust NdotL so that
    // the range of values for highlight/shading is narrower
    // with lower light intensity
    // and with lighter/brighter surface colors
    NdotL = mix((1.0 - u_lightintensity), max((1.0 - colorvalue + u_lightintensity), 1.0), NdotL);
#endif

    // Add gradient along z axis of side surfaces
    if (normal.y != 0.0) {
        float r = 0.84;
#ifndef LIGHTING_3D_MODE
        r = mix(0.7, 0.98, 1.0 - u_lightintensity);
#endif
        // This avoids another branching statement, but multiplies by a constant of 0.84 if no vertical gradient,
        // and otherwise calculates the gradient based on base + height
        NdotL *= (
            (1.0 - u_vertical_gradient) +
            (u_vertical_gradient * clamp((t + base) * pow(height / 150.0, 0.5), r, 1.0)));
    }

    v_color = vec4(0.0, 0.0, 0.0, 1.0);

#ifdef FAUX_AO
    // Documented at https://github.com/mapbox/mapbox-gl-js/pull/11926#discussion_r898496259
    float concave = pos_nx.w - floor(pos_nx.w * 0.5) * 2.0;
    float start = top_up_ny_start.w;
    float y_ground = 1.0 - clamp(t + base, 0.0, 1.0);
    float top_height = height;
#ifdef TERRAIN
    top_height = mix(max(c_ele + height, ele + base + 2.0), ele + height, float(centroid_pos.x == 0.0)) - ele;
    y_ground += y_ground * 5.0 / max(3.0, top_height);
#endif
    v_ao = vec3(mix(concave, -concave, start), y_ground, h - ele);
    NdotL *= (1.0 + 0.05 * (1.0 - top_up_ny.y) * u_ao[0]); // compensate sides faux ao shading contribution

#ifdef PROJECTION_GLOBE_VIEW
    top_height += u_height_lift;
#endif
    gl_Position.z -= (0.0000006 * (min(top_height, 500.) + 2.0 * min(base, 500.0) + 60.0 * concave + 3.0 * start)) * gl_Position.w;
#endif

#ifdef LIGHTING_3D_MODE
    v_color = apply_lighting(color, NdotL);
#else
    // Assign final color based on surface + ambient light color, diffuse light NdotL, and light color
    // with lower bounds adjusted to hue of light
    // so that shading is tinted with the complementary (opposite) color to the light color
    v_color.rgb += clamp(color.rgb * NdotL * u_lightcolor, mix(vec3(0.0), vec3(0.3), 1.0 - u_lightcolor), vec3(1.0));
#endif
    
    v_color *= u_opacity;

#ifdef ZERO_ROOF_RADIUS
    v_roof_color = vec4(0.0, 0.0, 0.0, 1.0);

#ifdef LIGHTING_3D_MODE
    v_roof_color = apply_lighting(color, calculate_NdotL(vec3(0.0, 0.0, 1.0)));
#else
    float roofNdotL = clamp(u_lightpos.z, 0.0, 1.0);
    roofNdotL = mix((1.0 - u_lightintensity), max((1.0 - colorvalue + u_lightintensity), 1.0), roofNdotL);
    v_roof_color.rgb += clamp(color.rgb * roofNdotL * u_lightcolor, mix(vec3(0.0), vec3(0.3), 1.0 - u_lightcolor), vec3(1.0));
#endif

    v_roof_color *= u_opacity;
#endif

#ifdef FOG
    v_fog_pos = fog_position(pos);
#endif
}