#ifdef QUANTIZATION_BITS12
attribute vec4 compressed0;
attribute float compressed1;
#else
attribute vec4 position3DAndHeight;
attribute vec4 textureCoordAndEncodedNormals;
#endif

#ifdef GEODETIC_SURFACE_NORMALS
attribute vec3 geodeticSurfaceNormal;
#endif

#ifdef EXAGGERATION
uniform vec2 u_terrainExaggerationAndRelativeHeight;
#endif

uniform vec3 u_center3D;
uniform mat4 u_modifiedModelView;
uniform mat4 u_modifiedModelViewProjection;
uniform vec4 u_tileRectangle;

// Uniforms for 2D Mercator projection
uniform vec2 u_southAndNorthLatitude;
uniform vec2 u_southMercatorYAndOneOverHeight;

varying vec3 v_positionMC;
varying vec3 v_positionEC;

varying vec3 v_textureCoordinates;
varying vec3 v_normalMC;
varying vec3 v_normalEC;

#ifdef APPLY_MATERIAL
varying float v_slope;
varying float v_aspect;
varying float v_height;
#endif

#if defined(FOG) || defined(GROUND_ATMOSPHERE) || defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT)
varying float v_distance;
#endif

#if defined(FOG) || defined(GROUND_ATMOSPHERE)
varying vec3 v_atmosphereRayleighColor;
varying vec3 v_atmosphereMieColor;
varying float v_atmosphereOpacity;
#endif

// These functions are generated at runtime.
vec4 getPosition(vec3 position, float height, vec2 textureCoordinates);
float get2DYPositionFraction(vec2 textureCoordinates);

vec4 getPosition3DMode(vec3 position, float height, vec2 textureCoordinates)
{
    return u_modifiedModelViewProjection * vec4(position, 1.0);
}

float get2DMercatorYPositionFraction(vec2 textureCoordinates)
{
    // The width of a tile at level 11, in radians and assuming a single root tile, is
    //   2.0 * czm_pi / pow(2.0, 11.0)
    // We want to just linearly interpolate the 2D position from the texture coordinates
    // when we're at this level or higher.  The constant below is the expression
    // above evaluated and then rounded up at the 4th significant digit.
    const float maxTileWidth = 0.003068;
    float positionFraction = textureCoordinates.y;
    float southLatitude = u_southAndNorthLatitude.x;
    float northLatitude = u_southAndNorthLatitude.y;
    if (northLatitude - southLatitude > maxTileWidth)
    {
        float southMercatorY = u_southMercatorYAndOneOverHeight.x;
        float oneOverMercatorHeight = u_southMercatorYAndOneOverHeight.y;

        float currentLatitude = mix(southLatitude, northLatitude, textureCoordinates.y);
        currentLatitude = clamp(currentLatitude, -czm_webMercatorMaxLatitude, czm_webMercatorMaxLatitude);
        positionFraction = czm_latitudeToWebMercatorFraction(currentLatitude, southMercatorY, oneOverMercatorHeight);
    }
    return positionFraction;
}

float get2DGeographicYPositionFraction(vec2 textureCoordinates)
{
    return textureCoordinates.y;
}

vec4 getPositionPlanarEarth(vec3 position, float height, vec2 textureCoordinates)
{
    float yPositionFraction = get2DYPositionFraction(textureCoordinates);
    vec4 rtcPosition2D = vec4(height, mix(u_tileRectangle.st, u_tileRectangle.pq, vec2(textureCoordinates.x, yPositionFraction)), 1.0);
    return u_modifiedModelViewProjection * rtcPosition2D;
}

vec4 getPosition2DMode(vec3 position, float height, vec2 textureCoordinates)
{
    return getPositionPlanarEarth(position, 0.0, textureCoordinates);
}

vec4 getPositionColumbusViewMode(vec3 position, float height, vec2 textureCoordinates)
{
    return getPositionPlanarEarth(position, height, textureCoordinates);
}

vec4 getPositionMorphingMode(vec3 position, float height, vec2 textureCoordinates)
{
    // We do not do RTC while morphing, so there is potential for jitter.
    // This is unlikely to be noticeable, though.
    vec3 position3DWC = position + u_center3D;
    float yPositionFraction = get2DYPositionFraction(textureCoordinates);
    vec4 position2DWC = vec4(height, mix(u_tileRectangle.st, u_tileRectangle.pq, vec2(textureCoordinates.x, yPositionFraction)), 1.0);
    vec4 morphPosition = czm_columbusViewMorph(position2DWC, vec4(position3DWC, 1.0), czm_morphTime);
    return czm_modelViewProjection * morphPosition;
}

#ifdef QUANTIZATION_BITS12
uniform vec2 u_minMaxHeight;
uniform mat4 u_scaleAndBias;
#endif

void main()
{
#ifdef QUANTIZATION_BITS12
    vec2 xy = czm_decompressTextureCoordinates(compressed0.x);
    vec2 zh = czm_decompressTextureCoordinates(compressed0.y);
    vec3 position = vec3(xy, zh.x);
    float height = zh.y;
    vec2 textureCoordinates = czm_decompressTextureCoordinates(compressed0.z);

    height = height * (u_minMaxHeight.y - u_minMaxHeight.x) + u_minMaxHeight.x;
    position = (u_scaleAndBias * vec4(position, 1.0)).xyz;

#if (defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL)) && defined(INCLUDE_WEB_MERCATOR_Y)
    float webMercatorT = czm_decompressTextureCoordinates(compressed0.w).x;
    float encodedNormal = compressed1;
#elif defined(INCLUDE_WEB_MERCATOR_Y)
    float webMercatorT = czm_decompressTextureCoordinates(compressed0.w).x;
    float encodedNormal = 0.0;
#elif defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL)
    float webMercatorT = textureCoordinates.y;
    float encodedNormal = compressed0.w;
#else
    float webMercatorT = textureCoordinates.y;
    float encodedNormal = 0.0;
#endif

#else
    // A single float per element
    vec3 position = position3DAndHeight.xyz;
    float height = position3DAndHeight.w;
    vec2 textureCoordinates = textureCoordAndEncodedNormals.xy;

#if (defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL) || defined(APPLY_MATERIAL)) && defined(INCLUDE_WEB_MERCATOR_Y)
    float webMercatorT = textureCoordAndEncodedNormals.z;
    float encodedNormal = textureCoordAndEncodedNormals.w;
#elif defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL) || defined(APPLY_MATERIAL)
    float webMercatorT = textureCoordinates.y;
    float encodedNormal = textureCoordAndEncodedNormals.z;
#elif defined(INCLUDE_WEB_MERCATOR_Y)
    float webMercatorT = textureCoordAndEncodedNormals.z;
    float encodedNormal = 0.0;
#else
    float webMercatorT = textureCoordinates.y;
    float encodedNormal = 0.0;
#endif

#endif

    vec3 position3DWC = position + u_center3D;

#ifdef GEODETIC_SURFACE_NORMALS
    vec3 ellipsoidNormal = geodeticSurfaceNormal;
#else
    vec3 ellipsoidNormal = normalize(position3DWC);
#endif

#if defined(EXAGGERATION) && defined(GEODETIC_SURFACE_NORMALS)
    float exaggeration = u_terrainExaggerationAndRelativeHeight.x;
    float relativeHeight = u_terrainExaggerationAndRelativeHeight.y;
    float newHeight = (height - relativeHeight) * exaggeration + relativeHeight;

    // stop from going through center of earth
    float minRadius = min(min(czm_ellipsoidRadii.x, czm_ellipsoidRadii.y), czm_ellipsoidRadii.z);
    newHeight = max(newHeight, -minRadius);

    vec3 offset = ellipsoidNormal * (newHeight - height);
    position += offset;
    position3DWC += offset;
    height = newHeight;
#endif

    gl_Position = getPosition(position, height, textureCoordinates);

    v_positionEC = (u_modifiedModelView * vec4(position, 1.0)).xyz;
    v_positionMC = position3DWC;  // position in model coordinates

    v_textureCoordinates = vec3(textureCoordinates, webMercatorT);

#if defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL) || defined(APPLY_MATERIAL)
    vec3 normalMC = czm_octDecode(encodedNormal);

#if defined(EXAGGERATION) && defined(GEODETIC_SURFACE_NORMALS)
    vec3 projection = dot(normalMC, ellipsoidNormal) * ellipsoidNormal;
    vec3 rejection = normalMC - projection;
    normalMC = normalize(projection + rejection * exaggeration);
#endif

    v_normalMC = normalMC;
    v_normalEC = czm_normal3D * v_normalMC;
#endif

#if defined(FOG) || (defined(GROUND_ATMOSPHERE) && !defined(PER_FRAGMENT_GROUND_ATMOSPHERE))

    bool dynamicLighting = false;

    #if defined(DYNAMIC_ATMOSPHERE_LIGHTING) && (defined(ENABLE_DAYNIGHT_SHADING) || defined(ENABLE_VERTEX_LIGHTING))
        dynamicLighting = true;
    #endif

#if defined(DYNAMIC_ATMOSPHERE_LIGHTING_FROM_SUN)
    vec3 atmosphereLightDirection = czm_sunDirectionWC;
#else
    vec3 atmosphereLightDirection = czm_lightDirectionWC;
#endif

    vec3 lightDirection = czm_branchFreeTernary(dynamicLighting, atmosphereLightDirection, normalize(position3DWC));

    computeAtmosphereScattering(
        position3DWC,
        lightDirection,
        v_atmosphereRayleighColor,
        v_atmosphereMieColor,
        v_atmosphereOpacity
    );
#endif

#if defined(FOG) || defined(GROUND_ATMOSPHERE) || defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT)
    v_distance = length((czm_modelView3D * vec4(position3DWC, 1.0)).xyz);
#endif

#ifdef APPLY_MATERIAL
    float northPoleZ = czm_ellipsoidRadii.z;
    vec3 northPolePositionMC = vec3(0.0, 0.0, northPoleZ);
    vec3 vectorEastMC = normalize(cross(northPolePositionMC - v_positionMC, ellipsoidNormal));
    float dotProd = abs(dot(ellipsoidNormal, v_normalMC));
    v_slope = acos(dotProd);
    vec3 normalRejected = ellipsoidNormal * dotProd;
    vec3 normalProjected = v_normalMC - normalRejected;
    vec3 aspectVector = normalize(normalProjected);
    v_aspect = acos(dot(aspectVector, vectorEastMC));
    float determ = dot(cross(vectorEastMC, aspectVector), ellipsoidNormal);
    v_aspect = czm_branchFreeTernary(determ < 0.0, 2.0 * czm_pi - v_aspect, v_aspect);
    v_height = height;
#endif
}
