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#pragma BLENDER_REQUIRE(common_view_lib.glsl)
vec3 weight_to_rgb(float weight)
{
vec3 r_rgb;
float blend = ((weight / 2.0) + 0.5);
if (weight <= 0.25) { /* blue->cyan */
r_rgb[0] = 0.0;
r_rgb[1] = blend * weight * 4.0;
r_rgb[2] = blend;
}
else if (weight <= 0.50) { /* cyan->green */
r_rgb[0] = 0.0;
r_rgb[1] = blend;
r_rgb[2] = blend * (1.0 - ((weight - 0.25) * 4.0));
}
else if (weight <= 0.75) { /* green->yellow */
r_rgb[0] = blend * ((weight - 0.50) * 4.0);
r_rgb[1] = blend;
r_rgb[2] = 0.0;
}
else if (weight <= 1.0) { /* yellow->red */
r_rgb[0] = blend;
r_rgb[1] = blend * (1.0 - ((weight - 0.75) * 4.0));
r_rgb[2] = 0.0;
}
else {
/* exceptional value, unclamped or nan,
* avoid uninitialized memory use */
r_rgb[0] = 1.0;
r_rgb[1] = 0.0;
r_rgb[2] = 1.0;
}
return r_rgb;
}
#define M_PI 3.1415926535897932
vec2 angle_to_v2(float angle)
{
return vec2(cos(angle), sin(angle));
}
/* Adapted from BLI_math_vector.h */
float angle_normalized_v2v2(vec2 v1, vec2 v2)
{
v1 = normalize(v1 * aspect);
v2 = normalize(v2 * aspect);
/* this is the same as acos(dot_v3v3(v1, v2)), but more accurate */
bool q = (dot(v1, v2) >= 0.0);
vec2 v = (q) ? (v1 - v2) : (v1 + v2);
float a = 2.0 * asin(length(v) / 2.0);
return (q) ? a : M_PI - a;
}
float area_ratio_to_stretch(float ratio, float tot_ratio)
{
ratio *= tot_ratio;
return (ratio > 1.0f) ? (1.0f / ratio) : ratio;
}
void main()
{
vec3 world_pos = point_object_to_world(vec3(pos, 0.0));
gl_Position = point_world_to_ndc(world_pos);
#ifdef STRETCH_ANGLE
vec2 v1 = angle_to_v2(uv_angles.x * M_PI);
vec2 v2 = angle_to_v2(uv_angles.y * M_PI);
float uv_angle = angle_normalized_v2v2(v1, v2) / M_PI;
float stretch = 1.0 - abs(uv_angle - angle);
stretch = stretch;
stretch = 1.0 - stretch * stretch;
#else
float stretch = 1.0 - area_ratio_to_stretch(ratio, totalAreaRatio);
#endif
finalColor = vec4(weight_to_rgb(stretch), 1.0);
}
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