ray_at_depth()

glm::vec3 MayaFlux::Kinesis::ray_at_depth ( double  window_x, double  window_y, uint32_t  width, uint32_t  height, float  ndc_depth, const ViewTransform &  vt  )

inline

Recover the world-space position at a known depth for a given pixel.

Unprojects a window pixel and a Vulkan NDC depth value [0, 1] back into world space by inverting the full view-projection transform. This is the inverse of what the vertex shader does: given the depth the GPU wrote into the depth attachment at (window_x, window_y), return the world position that produced it.

The depth value must be in Vulkan's [0, 1] range (not OpenGL's [-1, 1]). Pass 0.0 to recover the near-plane position, 1.0 for the far plane. A value sampled from the depth attachment is valid directly.

Parameters

window_x	X in window space [0, width] (top-left origin).
window_y	Y in window space [0, height] (top-left origin).
width	Window width in pixels.
height	Window height in pixels.
ndc_depth	Depth in [0, 1] (Vulkan convention).
vt	Active ViewTransform (view + projection matrices).

Returns

World-space position corresponding to the pixel at that depth.

Definition at line 198 of file HitTest.hpp.

{
    float ndc_x = (static_cast<float>(window_x) / static_cast<float>(width)) * 2.0F - 1.0F;
    float ndc_y = 1.0F - (static_cast<float>(window_y) / static_cast<float>(height)) * 2.0F;
 
    glm::mat4 inv_vp = glm::inverse(vt.projection * vt.view);
    glm::vec4 h = inv_vp * glm::vec4(ndc_x, ndc_y, ndc_depth, 1.0F);
    return glm::vec3(h) / h.w;
}

References h, MayaFlux::Kinesis::ViewTransform::projection, MayaFlux::Kinesis::ViewTransform::view, and width.