#version 300 es

layout(location = 0) in vec2 a_pos;
layout(location = 1) in vec2 a_tex_coord;

const float PI = 3.141592653589793;
uniform mat4 u_projection_matrix;
#define GLOBE_RADIUS 6371008.8
uniform highp vec4 u_projection_tile_mercator_coords;
uniform highp vec4 u_projection_clipping_plane;
uniform highp float u_projection_transition;
uniform mat4 u_projection_fallback_matrix;

vec3 globeRotateVector(vec3 vec,vec2 angles) {
    vec3 axisRight=vec3(vec.z,0.0,-vec.x);
    vec3 axisUp=cross(axisRight,vec);
    axisRight=normalize(axisRight);
    axisUp=normalize(axisUp);
    vec2 t=tan(angles);
    return normalize(vec+axisRight*t.x+axisUp*t.y);
}

mat3 globeGetRotationMatrix(vec3 spherePos) {
    vec3 axisRight=vec3(spherePos.z,0.0,-spherePos.x);
    vec3 axisDown=cross(axisRight,spherePos);
    axisRight=normalize(axisRight);
    axisDown=normalize(axisDown);
    return mat3(axisRight,axisDown,spherePos);
}

float circumferenceRatioAtTileY(float tileY) {
    float mercator_pos_y = u_projection_tile_mercator_coords.y + u_projection_tile_mercator_coords.w*tileY;
    float spherical_y = 2.0*atan(exp(PI-(mercator_pos_y*PI*2.0))) - PI*0.5;return cos(spherical_y);
}

float projectLineThickness(float tileY) {
    float thickness=1.0/circumferenceRatioAtTileY(tileY); 
    if (u_projection_transition < 0.999) {
        return mix(1.0,thickness,u_projection_transition);
    } else {
        return thickness;
    }
}

vec3 projectToSphere(vec2 translatedPos,vec2 rawPos) {
    vec2 mercator_pos = u_projection_tile_mercator_coords.xy+u_projection_tile_mercator_coords.zw*translatedPos;
    vec2 spherical;
    spherical.x=mercator_pos.x*PI*2.0+PI;
    spherical.y=2.0*atan(exp(PI-(mercator_pos.y*PI*2.0)))-PI*0.5;
    float len=cos(spherical.y);
    vec3 pos=vec3(sin(spherical.x)*len,sin(spherical.y),cos(spherical.x)*len);
    if (rawPos.y <-32767.5) {
        pos = vec3(0.0,1.0,0.0);
    }
    if (rawPos.y > 32766.5) {
        pos=vec3(0.0,-1.0,0.0);
    }
    
    return pos;
}

vec3 projectToSphere(vec2 posInTile) {
    return projectToSphere(posInTile,vec2(0.0,0.0));
}

float globeComputeClippingZ(vec3 spherePos) {
    return (1.0-(dot(spherePos,u_projection_clipping_plane.xyz)+u_projection_clipping_plane.w));
}

vec4 interpolateProjection(vec2 posInTile,vec3 spherePos,float elevation) {
    vec3 elevatedPos=spherePos*(1.0+elevation/GLOBE_RADIUS);
    vec4 globePosition=u_projection_matrix*vec4(elevatedPos,1.0);
    globePosition.z=globeComputeClippingZ(elevatedPos)*globePosition.w;

    if (u_projection_transition > 0.999) {return globePosition;}

    vec4 flatPosition=u_projection_fallback_matrix*vec4(posInTile,elevation,1.0);
    const float z_globeness_threshold=0.2;
    
    vec4 result=globePosition;result.z=mix(0.0,globePosition.z,clamp((u_projection_transition-z_globeness_threshold)/(1.0-z_globeness_threshold),0.0,1.0));result.xyw=mix(flatPosition.xyw,globePosition.xyw,u_projection_transition);if ((posInTile.y <-32767.5) || (posInTile.y > 32766.5)) {result=globePosition;const float poles_hidden_anim_percentage=0.02;result.z=mix(globePosition.z,100.0,pow(max((1.0-u_projection_transition)/poles_hidden_anim_percentage,0.0),8.0));}return result;}vec4 interpolateProjectionFor3D(vec2 posInTile,vec3 spherePos,float elevation) {vec3 elevatedPos=spherePos*(1.0+elevation/GLOBE_RADIUS);vec4 globePosition=u_projection_matrix*vec4(elevatedPos,1.0);
    
    if (u_projection_transition > 0.999) {return globePosition;}
    
    vec4 fallbackPosition=u_projection_fallback_matrix*vec4(posInTile,elevation,1.0);
    return mix(fallbackPosition,globePosition,u_projection_transition);
}

vec4 projectTile(vec2 posInTile) {
    return interpolateProjection(posInTile,projectToSphere(posInTile),0.0);
}

vec4 projectTile(vec2 posInTile,vec2 rawPos) {
    return interpolateProjection(posInTile,projectToSphere(posInTile,rawPos),0.0);
}

vec4 projectTileWithElevation(vec2 posInTile,float elevation) {
    return interpolateProjection(posInTile,projectToSphere(posInTile),elevation);
}

vec4 projectTileFor3D(vec2 posInTile,float elevation) {
    vec3 spherePos=projectToSphere(posInTile,posInTile);
    return interpolateProjectionFor3D(posInTile,spherePos,elevation);
}

#define GLOBE

out vec2 v_tex_coord;

void main() {
    gl_Position = projectTile(a_pos);
    v_tex_coord = a_tex_coord;
}