/*******************************************************************************************
*
*   rPBR [shader] - Equirectangular to cubemap fragment shader
*
*   Copyright (c) 2017 Victor Fisac
*
**********************************************************************************************/

#version 330

# Input vertex attributes (from vertex shader)
in vec3 fragPos

# Input uniform values
uniform sampler2D equirectangularMap

# Output fragment color
out vec4 finalColor

vec2 SampleSphericalMap(vec3 v)
[
    vec2 uv = vec2(atan(v.z, v.x), asin(v.y))
    uv *= vec2(0.1591, 0.3183)
    uv += 0.5
    return uv
]

void main()
[
    # Normalize local position
    vec2 uv = SampleSphericalMap(normalize(fragPos))

    # Fetch color from texture map
    vec3 color = texture(equirectangularMap, uv).rgb

    # Calculate final fragment color
    finalColor = vec4(color, 1.0)
]