// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.

#include <mbgl/shaders/preludes.hpp>

namespace mbgl {
namespace shaders {

const char* vertexPrelude = R"MBGL_SHADER(
#ifdef GL_ES
precision highp float;
#else

#if !defined(lowp)
#define lowp
#endif

#if !defined(mediump)
#define mediump
#endif

#if !defined(highp)
#define highp
#endif

#endif

float evaluate_zoom_function_1(const vec4 values, const float t) {
    if (t < 1.0) {
        return mix(values[0], values[1], t);
    } else if (t < 2.0) {
        return mix(values[1], values[2], t - 1.0);
    } else {
        return mix(values[2], values[3], t - 2.0);
    }
}
vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
    if (t < 1.0) {
        return mix(value0, value1, t);
    } else if (t < 2.0) {
        return mix(value1, value2, t - 1.0);
    } else {
        return mix(value2, value3, t - 2.0);
    }
}

// Unpack a pair of values that have been packed into a single float.
// The packed values are assumed to be 8-bit unsigned integers, and are
// packed like so:
// packedValue = floor(input[0]) * 256 + input[1],
vec2 unpack_float(const float packedValue) {
    float v0 = floor(packedValue / 256.0);
    return vec2(v0, packedValue - v0 * 256.0);
}


// To minimize the number of attributes needed in the mapbox-gl-native shaders,
// we encode a 4-component color into a pair of floats (i.e. a vec2) as follows:
// [ floor(color.r * 255) * 256 + color.g * 255,
//   floor(color.b * 255) * 256 + color.g * 255 ]
vec4 decode_color(const vec2 encodedColor) {
    return vec4(
        unpack_float(encodedColor[0]) / 255.0,
        unpack_float(encodedColor[1]) / 255.0
    );
}

// Unpack a pair of paint values and interpolate between them.
float unpack_mix_vec2(const vec2 packedValue, const float t) {
    return mix(packedValue[0], packedValue[1], t);
}

// Unpack a pair of paint values and interpolate between them.
vec4 unpack_mix_vec4(const vec4 packedColors, const float t) {
    vec4 minColor = decode_color(vec2(packedColors[0], packedColors[1]));
    vec4 maxColor = decode_color(vec2(packedColors[2], packedColors[3]));
    return mix(minColor, maxColor, t);
}

// The offset depends on how many pixels are between the world origin and the edge of the tile:
// vec2 offset = mod(pixel_coord, size)
//
// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
//
// The pixel_coord is passed in as two 16 bit values:
// pixel_coord_upper = floor(pixel_coord / 2^16)
// pixel_coord_lower = mod(pixel_coord, 2^16)
//
// The offset is calculated in a series of steps that should preserve this precision:
vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {

    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
    return (tile_units_to_pixels * pos + offset) / pattern_size;
}

)MBGL_SHADER";
const char* fragmentPrelude = R"MBGL_SHADER(
#ifdef GL_ES
precision mediump float;
#else

#if !defined(lowp)
#define lowp
#endif

#if !defined(mediump)
#define mediump
#endif

#if !defined(highp)
#define highp
#endif

#endif

)MBGL_SHADER";

} // namespace shaders
} // namespace mbgl