The open source OpenXR runtime
u/distortion: Add simple cardboard distortion code
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src/xrt/auxiliary/CMakeLists.txt
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src/xrt/auxiliary/CMakeLists.txt
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src/xrt/auxiliary/meson.build
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src/xrt/auxiliary/meson.build
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src/xrt/auxiliary/util/u_distortion.c
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src/xrt/auxiliary/util/u_distortion.c
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// Copyright 2020, Collabora, Ltd.
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// SPDX-License-Identifier: BSL-1.0
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/*!
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* @file
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* @brief Code to handle distortion parameters and fov.
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* @author Jakob Bornecrantz <jakob@collabora.com>
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* @ingroup aux_distortion
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*/
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#include "xrt/xrt_device.h"
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#include "math/m_mathinclude.h"
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#include "util/u_misc.h"
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#include "util/u_device.h"
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#include "util/u_distortion.h"
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void
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u_distortion_cardboard_calculate(
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const struct u_cardboard_distortion_arguments *args,
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struct xrt_hmd_parts *parts,
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struct u_cardboard_distortion *out_dist)
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{
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/*
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* HMD parts
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*/
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uint32_t w_pixels = args->screen.w_pixels / 2;
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uint32_t h_pixels = args->screen.h_pixels;
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// Use the full screen.
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parts->screens[0].w_pixels = args->screen.w_pixels;
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parts->screens[0].h_pixels = args->screen.h_pixels;
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parts->views[0].viewport.x_pixels = 0;
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parts->views[0].viewport.y_pixels = 0;
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parts->views[0].viewport.w_pixels = w_pixels;
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parts->views[0].viewport.h_pixels = h_pixels;
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parts->views[0].display.w_pixels = w_pixels;
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parts->views[0].display.h_pixels = h_pixels;
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parts->views[0].rot = u_device_rotation_ident;
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parts->views[0].fov = args->fov;
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parts->views[1].viewport.x_pixels = w_pixels;
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parts->views[1].viewport.y_pixels = 0;
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parts->views[1].viewport.w_pixels = w_pixels;
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parts->views[1].viewport.h_pixels = h_pixels;
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parts->views[1].display.w_pixels = w_pixels;
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parts->views[1].display.h_pixels = h_pixels;
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parts->views[1].rot = u_device_rotation_ident;
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parts->views[1].fov = args->fov;
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/*
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* Left values
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*/
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// clang-format off
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struct u_cardboard_distortion_values l_values = {0};
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l_values.distortion_k[0] = args->distortion_k[0];
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l_values.distortion_k[1] = args->distortion_k[1];
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l_values.distortion_k[2] = args->distortion_k[2];
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l_values.distortion_k[3] = args->distortion_k[3];
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l_values.distortion_k[4] = args->distortion_k[4];
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l_values.screen.size.x = args->screen.w_meters;
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l_values.screen.size.y = args->screen.h_meters;
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l_values.screen.offset.x = (args->screen.w_meters - args->inter_lens_distance_meters) / 2.0;
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l_values.screen.offset.y = args->lens_y_center_on_screen_meters;
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// clang-format on
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// Turn into tanangles
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l_values.screen.size.x /= args->screen_to_lens_distance_meters;
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l_values.screen.size.y /= args->screen_to_lens_distance_meters;
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l_values.screen.offset.x /= args->screen_to_lens_distance_meters;
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l_values.screen.offset.y /= args->screen_to_lens_distance_meters;
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// Tan-angle to texture coordinates
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// clang-format off
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l_values.texture.size.x = tan(-args->fov.angle_left) + tan(args->fov.angle_right);
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l_values.texture.size.y = tan(args->fov.angle_up) + tan(-args->fov.angle_down);
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l_values.texture.offset.x = tan(-args->fov.angle_left);
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l_values.texture.offset.y = tan(-args->fov.angle_down);
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// clang-format on
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// Fix up views not covering the entire screen.
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l_values.screen.size.x /= 2.0;
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/*
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* Right values
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*/
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// clang-format off
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struct u_cardboard_distortion_values r_values = {0};
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r_values.distortion_k[0] = args->distortion_k[0];
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r_values.distortion_k[1] = args->distortion_k[1];
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r_values.distortion_k[2] = args->distortion_k[2];
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r_values.distortion_k[3] = args->distortion_k[3];
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r_values.distortion_k[4] = args->distortion_k[4];
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r_values.screen.size.x = args->screen.w_meters;
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r_values.screen.size.y = args->screen.h_meters;
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r_values.screen.offset.x = (args->screen.w_meters + args->inter_lens_distance_meters) / 2.0;
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r_values.screen.offset.y = args->lens_y_center_on_screen_meters;
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// clang-format on
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// Turn into tanangles
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r_values.screen.size.x /= args->screen_to_lens_distance_meters;
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r_values.screen.size.y /= args->screen_to_lens_distance_meters;
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r_values.screen.offset.x /= args->screen_to_lens_distance_meters;
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r_values.screen.offset.y /= args->screen_to_lens_distance_meters;
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// Tanangle to texture coordinates
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// clang-format off
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r_values.texture.size.x = tan(-args->fov.angle_left) + tan(args->fov.angle_right);
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r_values.texture.size.y = tan(args->fov.angle_up) + tan(-args->fov.angle_down);
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r_values.texture.offset.x = tan(-args->fov.angle_left);
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r_values.texture.offset.y = tan(-args->fov.angle_down);
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// clang-format on
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// Fix up views not covering the entire screen.
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r_values.screen.size.x /= 2.0;
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r_values.screen.offset.x -= r_values.screen.size.x;
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/*
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* Write results.
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*/
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// Copy the arguments.
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out_dist->args = *args;
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// Save the results.
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out_dist->values[0] = l_values;
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out_dist->values[1] = r_values;
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}
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src/xrt/auxiliary/util/u_distortion.h
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src/xrt/auxiliary/util/u_distortion.h
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// Copyright 2020, Collabora, Ltd.
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// SPDX-License-Identifier: BSL-1.0
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/*!
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* @file
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* @brief Code to handle distortion parameters and fov.
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* @author Jakob Bornecrantz <jakob@collabora.com>
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* @ingroup aux_distortion
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*/
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#pragma once
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#include "xrt/xrt_defines.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct xrt_hmd_parts;
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/*!
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* @defgroup aux_distortion Distortion utilities.
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* @ingroup aux_util
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*/
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/*!
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* These are the values that you need to supply to the distortion code to setup
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* a @ref u_cardboard_distortion properly.
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*
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* @ingroup aux_distortion
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*/
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struct u_cardboard_distortion_arguments
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{
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float distortion_k[5];
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struct
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{
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uint32_t w_pixels, h_pixels;
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float w_meters, h_meters;
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} screen;
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//! Distances between the lenses in meters.
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float inter_lens_distance_meters;
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//! Where on the y axis the center of the lens is on the screen.
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float lens_y_center_on_screen_meters;
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/*!
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* The distance to the lens from the screen, used to calculate calculate
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* tanangle of various distances on the screen.
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*/
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float screen_to_lens_distance_meters;
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//! Fov values that the cardboard configuration has given us.
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struct xrt_fov fov;
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};
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/*!
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* Values to create a distortion mesh from cardboard values.
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*
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* This matches the formula in the cardboard SDK, while the array is fixed size
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* just setting the K value to zero will make it not have a effect.
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*
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* p' = p (1 + K0 r^2 + K1 r^4 + ... + Kn r^(2n))
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*
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* @ingroup aux_distortion
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*/
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struct u_cardboard_distortion_values
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{
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//! Cardboard distortion k values.
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float distortion_k[5];
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struct
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{
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//! Used to transform to and from tanangle space.
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struct xrt_vec2 size;
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//! Used to transform to and from tanangle space.
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struct xrt_vec2 offset;
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} screen, texture;
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};
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/*!
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* Both given and derived values needed for cardboard distortion.
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*
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* @ingroup aux_distortion
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*/
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struct u_cardboard_distortion
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{
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//! Arguments this distortion was created from.
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struct u_cardboard_distortion_arguments args;
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//! Distortion parameters, some derived from @ref args.
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struct u_cardboard_distortion_values values[2];
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};
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/*!
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* Take cardboard arguments to turn them into a @ref u_cardboard_distortion and
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* fill out a @ref xrt_hmd_parts struct.
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*
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* @ingroup aux_distortion
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*/
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void
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u_distortion_cardboard_calculate(
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const struct u_cardboard_distortion_arguments *args,
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struct xrt_hmd_parts *parts,
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struct u_cardboard_distortion *out_dist);
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#ifdef __cplusplus
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}
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#endif
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src/xrt/auxiliary/util/u_distortion_mesh.c
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src/xrt/auxiliary/util/u_distortion_mesh.c
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* @file
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* @brief Code to generate disortion meshes.
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* @author Jakob Bornecrantz <jakob@collabora.com>
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* @ingroup aux_util
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* @ingroup aux_distortion
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*/
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#include "util/u_misc.h"
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#define div m_vec2_div
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#define div_scalar m_vec2_div_scalar
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#define len m_vec2_len
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#define len_sqrd m_vec2_len_sqrd
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bool
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u_compute_distortion_panotools(struct u_panotools_values *values,
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result->r = r_uv;
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result->g = g_uv;
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result->b = b_uv;
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return true;
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}
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bool
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u_compute_distortion_cardboard(struct u_cardboard_distortion_values *values,
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float u,
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float v,
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struct xrt_uv_triplet *result)
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{
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struct xrt_vec2 uv = {u, v};
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uv = sub(mul(uv, values->screen.size), values->screen.offset);
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float sqrd = len_sqrd(uv);
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float r = 1.0f;
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float fact = 1.0f;
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r *= sqrd;
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fact += values->distortion_k[0] * r;
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r *= sqrd;
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fact += values->distortion_k[1] * r;
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r *= sqrd;
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fact += values->distortion_k[2] * r;
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r *= sqrd;
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fact += values->distortion_k[3] * r;
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r *= sqrd;
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fact += values->distortion_k[4] * r;
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uv = mul_scalar(uv, fact);
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uv = div(add(uv, values->texture.offset), values->texture.size);
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result->r.x = uv.x;
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result->r.y = uv.y;
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result->g.x = uv.x;
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result->g.y = uv.y;
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result->b.x = uv.x;
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result->b.y = uv.y;
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return true;
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}
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src/xrt/auxiliary/util/u_distortion_mesh.h
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src/xrt/auxiliary/util/u_distortion_mesh.h
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* @file
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* @brief Code to generate disortion meshes.
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* @author Jakob Bornecrantz <jakob@collabora.com>
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* @ingroup aux_util
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* @ingroup aux_distortion
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*/
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#pragma once
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#include "xrt/xrt_device.h"
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#include "xrt/xrt_defines.h"
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#include "util/u_distortion.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*!
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* @ingroup aux_util
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* @{
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*/
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/*
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*
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* Panotools distortion
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/*!
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* Values to create a distortion mesh from panotools values.
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*
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* @ingroup aux_distortion
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*/
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struct u_panotools_values
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{
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/*!
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* Distortion correction implementation for Panotools distortion values.
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*
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* @ingroup aux_distortion
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*/
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bool
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u_compute_distortion_panotools(struct u_panotools_values *values,
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/*!
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* Values to create a distortion mesh from Vive configuration values.
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*
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* @ingroup aux_distortion
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*/
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struct u_vive_values
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{
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/*!
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* Distortion correction implementation for the Vive, Vive Pro, Valve Index
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* distortion values found in the HMD configuration.
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*
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* @ingroup aux_distortion
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*/
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bool
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u_compute_distortion_vive(struct u_vive_values *values,
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/*
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*
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* Cardboard mesh distortion parameters.
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*
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*/
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/*!
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* Distortion correction implementation for the Cardboard devices.
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*
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* @ingroup aux_distortion
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*/
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bool
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u_compute_distortion_cardboard(struct u_cardboard_distortion_values *values,
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float u,
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float v,
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struct xrt_uv_triplet *result);
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/*
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*
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* None distortion
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*
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*/
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/*!
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* Identity distortion correction sets all result coordinates to u,v.
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*
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* @ingroup aux_distortion
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*/
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bool
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u_compute_distortion_none(float u, float v, struct xrt_uv_triplet *result);
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/*!
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* Helper function for none distortion devices.
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*
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* @ingroup aux_distortion
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*/
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bool
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u_distortion_mesh_none(struct xrt_device *xdev,
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* xdev->compute_distortion(), populates `xdev->hmd_parts.distortion.mesh` &
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* `xdev->hmd_parts.distortion.models`.
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*
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* @ingroup aux_util
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* @relatesalso xrt_device
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* @ingroup aux_distortion
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*/
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void
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u_distortion_mesh_fill_in_compute(struct xrt_device *xdev);
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* `xdev->hmd_parts.distortion.mesh` & `xdev->hmd_parts.distortion.models`.
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*
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* @relatesalso xrt_device
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* @ingroup aux_distortion
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*/
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void
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u_distortion_mesh_fill_in_none(struct xrt_device *xdev);
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* & `xdev->hmd_parts.distortion.models`.
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*
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* @relatesalso xrt_device
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* @ingroup aux_distortion
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*/
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void
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u_distortion_mesh_set_none(struct xrt_device *xdev);
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/*!
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* @}
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*/
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#ifdef __cplusplus