threepipe/src/utils/shaders/cameraHelpers.glsl

#ifndef BASIC_CAMERA_HELPERS
#define BASIC_CAMERA_HELPERS

// See also PerspectiveCamera2
uniform mat4 projection;
uniform vec2 cameraNearFar;
uniform vec3 cameraPositionWorld;

#ifndef THREE_PACKING_INCLUDED
#define THREE_PACKING_INCLUDED
#include <packing>
#endif

float linstep(float edge0, float edge1, float value) {
    return clamp((value-edge0)/(edge1-edge0), 0.0, 1.0);
}

float depthToViewZ(const in float depth){
    return (depth > 0.999) ? -cameraNearFar.y * 1000.0 : -mix(cameraNearFar.x, cameraNearFar.y, depth);
}
float viewZToDepth(const in float viewZ){
    return linstep(-cameraNearFar.x, -cameraNearFar.y, viewZ);
}

vec4 viewToScreen3(const in vec3 pos) {
    vec4 projected = projection * vec4(pos, 1.0);
    projected.z = pos.z;
    // w is -viewZ
    projected.w = 1./projected.w;
    projected.xyz *= projected.w;
    projected.xy = 0.5 + 0.5 * projected.xy;
    return projected;
}

vec3 screenToView(const in vec2 uv, const in float viewZ) {
    vec2 uv_ = 2. * uv - 1.;
    float xe = -(uv_.x + projection[2][0]) * viewZ / projection[0][0];
    float ye = -(uv_.y + projection[2][1]) * viewZ / projection[1][1];
    return vec3(xe, ye, viewZ);
}

float viewZFromNDCZ(const in float depth) {
    #if PERSPECTIVE_CAMERA == 1
    return perspectiveDepthToViewZ(depth, cameraNearFar.x, cameraNearFar.y);
    #else
    return orthographicDepthToViewZ(depth, cameraNearFar.x, cameraNearFar.y);
    #endif
}


#endif