OpenSpace/modules/space/shaders/star_fs.glsl

/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2019                                                               *
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#include "fragment.glsl"
#include "floatoperations.glsl"

// keep in sync with renderablestars.h:ColorOption enum
const int COLOROPTION_COLOR     = 0;
const int COLOROPTION_VELOCITY  = 1; 
const int COLOROPTION_SPEED     = 2;
const int COLOROPTION_OTHERDATA = 3;

uniform sampler1D colorTexture;
uniform sampler2D psfTexture;
uniform float alphaValue;

uniform int colorOption;

uniform sampler1D otherDataTexture;
uniform vec2 otherDataRange;
uniform bool filterOutOfRange;

in vec4 vs_position;
in vec2 psfCoords;
flat in vec4 ge_bvLumAbsMagAppMag;
flat in vec3 ge_velocity;
flat in float ge_speed;
flat in float ge_observationDistance;
flat in float gs_screenSpaceDepth;

vec4 bv2rgb(float bv) {
    // BV is [-0.4,2.0]
    float t = (bv + 0.4) / (2.0 + 0.4);
    return texture(colorTexture, t);
}

bool isOtherDataValueInRange() {
    float t = (ge_bvLumAbsMagAppMag.x - otherDataRange.x) / (otherDataRange.y - otherDataRange.x);
    return t >= 0.0 && t <= 1.0;
}
vec4 otherDataValue() {
    float t = (ge_bvLumAbsMagAppMag.x - otherDataRange.x) / (otherDataRange.y - otherDataRange.x);
    t = clamp(t, 0.0, 1.0);
    return texture(otherDataTexture, t);
}

Fragment getFragment() {
    // Something in the color calculations need to be changed because before it was dependent
    // on the gl blend functions since the abuffer was not involved

    vec4 color = vec4(0.0);
    switch (colorOption) {
        case COLOROPTION_COLOR: 
            color = bv2rgb(ge_bvLumAbsMagAppMag.x);
            break;
        case COLOROPTION_VELOCITY:
            color = vec4(abs(ge_velocity), 0.5);
            break;
        case COLOROPTION_SPEED:
            // @TODO Include a transfer function here ---abock
            color = vec4(vec3(ge_speed), 0.5);
            break;
        case COLOROPTION_OTHERDATA:
            if (filterOutOfRange && !isOtherDataValueInRange()) {
                discard;
            }
            else {
                color = otherDataValue();
            }
            break;
    }

    vec4 textureColor = texture(psfTexture, 0.5*psfCoords + 0.5);
    vec4 fullColor = vec4(color.rgb, textureColor.a);
    fullColor.a *= alphaValue;
    
    if (fullColor.a == 0) {
        discard;
    }

    Fragment frag;
    frag.color     = fullColor;
    frag.depth     = gs_screenSpaceDepth;
    frag.gPosition = vs_position;
    frag.gNormal   = vec4(0.0, 0.0, 0.0, 1.0);
    
    return frag;
}