OpenSpace/shaders/PowerScaling/powerScaling_vs.hglsl

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2020                                                               *
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#ifndef POWERSCALING_VS_H_HGLSL
#define POWERSCALING_VS_H_HGLSL

uniform vec4 campos;
uniform mat4 camrot;
uniform vec2 scaling;
uniform vec4 objpos;

#include "powerScalingMath.hglsl"

vec4 psc_to_meter(vec4 v1, vec2 v2) {
    float factor = v2.x * pow(k,v2.y + v1.w);
    return vec4(v1.xyz * factor, 1.0);
}

vec4 psc_scaling(vec4 v1, vec2 v2) {
    float ds = v2.y - v1.w;
    if(ds >= 0) {
        return vec4(v1.xyz * v2.x * pow(k,v1.w), v2.y);
    } else {
        return vec4(v1.xyz * v2.x * pow(k,v2.y), v1.w);
    }
}

// vertexPosition is returned as the transformed vertex in OS Camera Rig Space in PSC
vec4 pscTransform(inout vec4 vertexPosition, mat4 modelTransform) {
    vec3 local_vertex_pos = mat3(modelTransform) * vertexPosition.xyz;
    
    // PSC addition; local vertex position and the object power scaled world position
    vertexPosition = psc_addition(vec4(local_vertex_pos,vertexPosition.w),objpos);
    
    // PSC addition; rotated and viewscaled vertex and the cameras negative position
    vertexPosition = psc_addition(vertexPosition,vec4(-campos.xyz,campos.w));
    
    // rotate the camera
    vertexPosition.xyz =  mat3(camrot) * vertexPosition.xyz;
    vec4 tmp = vertexPosition;
    vertexPosition = psc_scaling(vertexPosition, scaling);
    
    // project using the rescaled coordinates,
    tmp = psc_to_meter(tmp, scaling);
    
    // Return the vertex tranformed to OS Camera Rig Space
    // in meters.
    return tmp;
}

#endif