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Adapt disc shader to handle asymmetric uncertainty intervals

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This commit is contained in:
Emma Broman
2020-10-16 17:01:35 +02:00
parent 68eb52c740
commit d31b20decf
1 changed files with 22 additions and 8 deletions
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30
modules/exoplanets/shaders/orbitdisc_fs.glsl
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@@ -56,12 +56,16 @@ Fragment getFragment() {
// Moving the origin to the center
vec2 st = (vs_st - vec2(0.5)) * 2.0;
float offsetLower = textureOffset.x;
float offsetUpper = textureOffset.y;
float offsetIntervalSize = offsetLower + offsetUpper;
float AUpper = semiMajorAxis;
float BUpper = semiMinorAxis(AUpper, eccentricity);
float CUpper = sqrt(AUpper*AUpper - BUpper*BUpper);
float outerApoapsisDistance = AUpper * (1 + eccentricity);
float ALower = AUpper - AstronomicalUnit * (textureOffset.x + textureOffset.y);
float ALower = AUpper - AstronomicalUnit * offsetIntervalSize;
float BLower = semiMinorAxis(ALower, eccentricity);
float CLower = sqrt(ALower*ALower - BLower*BLower);
float innerApoapsisDistance = ALower * (1 + eccentricity);
@@ -91,18 +95,28 @@ Fragment getFragment() {
// Find outer ellipse: where along the direction does the equation == 1?
float denominator = pow(BU_n * dir.x, 2.0) + pow(AU_n * dir.y, 2.0);
float first = -(pow(BU_n, 2.0) * dir.x * CU_n) / denominator;
float second = pow((pow(BU_n, 2.0) * dir.x * CU_n) / denominator, 2.0);
float first = -(BU_n * BU_n * dir.x * CU_n) / denominator;
float second = pow((BU_n * BU_n * dir.x * CU_n) / denominator, 2.0);
float third = (pow(BU_n * CU_n, 2.0) - pow(AU_n * BU_n, 2.0)) / denominator;
float scale = first + sqrt(second - third);
vec2 max = dir * scale;
vec2 min = max * (innerApoapsisDistance / outerApoapsisDistance);
vec2 outerPoint = dir * scale;
vec2 innerPoint = outerPoint * (innerApoapsisDistance / outerApoapsisDistance);
float distance1 = distance(max, min);
float distance2 = distance(max, st);
float textureCoord = distance2 / distance1;
float discWidth = distance(outerPoint, innerPoint);
float distanceFromOuterEdge = distance(outerPoint, st);
float textureCoord = distanceFromOuterEdge / discWidth;
// Scale texture coordinate to handle asymmetric offset intervals
float textureMid = offsetUpper / offsetIntervalSize;
if(textureCoord > textureMid) {
textureCoord = 0.5 + 0.5 * (textureCoord - textureMid) / (1.0 - textureMid);
}
else {
textureCoord = 0.5 * textureCoord / textureMid;
}
vec4 diffuse = texture(discTexture, textureCoord);
diffuse.a *= opacity;