bd327e3bf3
When converting from XYZ to RGB it can happen, in some sky models, that the resulting RGB values are negative. Atm, this is not considered and the returned values for the sky model can be negative. This patch clamps the returned RGB values to be `= 0.f` Reviewed By: brecht, sergey Differential Revision: https://developer.blender.org/D14777
321 lines
10 KiB
C
321 lines
10 KiB
C
/* SPDX-License-Identifier: Apache-2.0
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* Copyright 2011-2022 Blender Foundation */
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#pragma once
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CCL_NAMESPACE_BEGIN
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/* Sky texture */
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ccl_device float sky_angle_between(float thetav, float phiv, float theta, float phi)
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{
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float cospsi = sinf(thetav) * sinf(theta) * cosf(phi - phiv) + cosf(thetav) * cosf(theta);
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return safe_acosf(cospsi);
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}
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/*
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* "A Practical Analytic Model for Daylight"
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* A. J. Preetham, Peter Shirley, Brian Smits
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*/
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ccl_device float sky_perez_function(ccl_private float *lam, float theta, float gamma)
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{
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float ctheta = cosf(theta);
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float cgamma = cosf(gamma);
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return (1.0f + lam[0] * expf(lam[1] / ctheta)) *
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(1.0f + lam[2] * expf(lam[3] * gamma) + lam[4] * cgamma * cgamma);
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}
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ccl_device float3 sky_radiance_preetham(KernelGlobals kg,
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float3 dir,
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float sunphi,
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float suntheta,
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float radiance_x,
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float radiance_y,
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float radiance_z,
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ccl_private float *config_x,
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ccl_private float *config_y,
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ccl_private float *config_z)
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{
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/* convert vector to spherical coordinates */
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float2 spherical = direction_to_spherical(dir);
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float theta = spherical.x;
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float phi = spherical.y;
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/* angle between sun direction and dir */
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float gamma = sky_angle_between(theta, phi, suntheta, sunphi);
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/* clamp theta to horizon */
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theta = min(theta, M_PI_2_F - 0.001f);
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/* compute xyY color space values */
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float x = radiance_y * sky_perez_function(config_y, theta, gamma);
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float y = radiance_z * sky_perez_function(config_z, theta, gamma);
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float Y = radiance_x * sky_perez_function(config_x, theta, gamma);
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/* convert to RGB */
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float3 xyz = xyY_to_xyz(x, y, Y);
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return xyz_to_rgb_clamped(kg, xyz);
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}
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/*
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* "An Analytic Model for Full Spectral Sky-Dome Radiance"
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* Lukas Hosek, Alexander Wilkie
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*/
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ccl_device float sky_radiance_internal(ccl_private float *configuration, float theta, float gamma)
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{
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float ctheta = cosf(theta);
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float cgamma = cosf(gamma);
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float expM = expf(configuration[4] * gamma);
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float rayM = cgamma * cgamma;
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float mieM = (1.0f + rayM) / powf((1.0f + configuration[8] * configuration[8] -
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2.0f * configuration[8] * cgamma),
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1.5f);
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float zenith = sqrtf(ctheta);
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return (1.0f + configuration[0] * expf(configuration[1] / (ctheta + 0.01f))) *
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(configuration[2] + configuration[3] * expM + configuration[5] * rayM +
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configuration[6] * mieM + configuration[7] * zenith);
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}
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ccl_device float3 sky_radiance_hosek(KernelGlobals kg,
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float3 dir,
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float sunphi,
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float suntheta,
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float radiance_x,
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float radiance_y,
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float radiance_z,
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ccl_private float *config_x,
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ccl_private float *config_y,
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ccl_private float *config_z)
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{
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/* convert vector to spherical coordinates */
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float2 spherical = direction_to_spherical(dir);
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float theta = spherical.x;
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float phi = spherical.y;
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/* angle between sun direction and dir */
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float gamma = sky_angle_between(theta, phi, suntheta, sunphi);
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/* clamp theta to horizon */
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theta = min(theta, M_PI_2_F - 0.001f);
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/* compute xyz color space values */
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float x = sky_radiance_internal(config_x, theta, gamma) * radiance_x;
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float y = sky_radiance_internal(config_y, theta, gamma) * radiance_y;
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float z = sky_radiance_internal(config_z, theta, gamma) * radiance_z;
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/* convert to RGB and adjust strength */
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return xyz_to_rgb_clamped(kg, make_float3(x, y, z)) * (M_2PI_F / 683);
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}
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/* Nishita improved sky model */
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ccl_device float3 geographical_to_direction(float lat, float lon)
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{
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return make_float3(cosf(lat) * cosf(lon), cosf(lat) * sinf(lon), sinf(lat));
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}
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ccl_device float3 sky_radiance_nishita(KernelGlobals kg,
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float3 dir,
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float3 pixel_bottom,
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float3 pixel_top,
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ccl_private float *nishita_data,
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uint texture_id)
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{
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/* definitions */
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float sun_elevation = nishita_data[0];
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float sun_rotation = nishita_data[1];
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float angular_diameter = nishita_data[2];
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float sun_intensity = nishita_data[3];
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bool sun_disc = (angular_diameter >= 0.0f);
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float3 xyz;
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/* convert dir to spherical coordinates */
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float2 direction = direction_to_spherical(dir);
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/* render above the horizon */
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if (dir.z >= 0.0f) {
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/* definitions */
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float3 sun_dir = geographical_to_direction(sun_elevation, sun_rotation + M_PI_2_F);
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float sun_dir_angle = precise_angle(dir, sun_dir);
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float half_angular = angular_diameter / 2.0f;
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float dir_elevation = M_PI_2_F - direction.x;
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/* if ray inside sun disc render it, otherwise render sky */
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if (sun_disc && sun_dir_angle < half_angular) {
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/* get 2 pixels data */
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float y;
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/* sun interpolation */
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if (sun_elevation - half_angular > 0.0f) {
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if (sun_elevation + half_angular > 0.0f) {
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y = ((dir_elevation - sun_elevation) / angular_diameter) + 0.5f;
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xyz = interp(pixel_bottom, pixel_top, y) * sun_intensity;
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}
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}
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else {
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if (sun_elevation + half_angular > 0.0f) {
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y = dir_elevation / (sun_elevation + half_angular);
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xyz = interp(pixel_bottom, pixel_top, y) * sun_intensity;
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}
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}
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/* limb darkening, coefficient is 0.6f */
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float limb_darkening = (1.0f -
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0.6f * (1.0f - sqrtf(1.0f - sqr(sun_dir_angle / half_angular))));
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xyz *= limb_darkening;
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}
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/* sky */
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else {
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/* sky interpolation */
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float x = (direction.y + M_PI_F + sun_rotation) / M_2PI_F;
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/* more pixels toward horizon compensation */
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float y = safe_sqrtf(dir_elevation / M_PI_2_F);
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if (x > 1.0f) {
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x -= 1.0f;
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}
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xyz = float4_to_float3(kernel_tex_image_interp(kg, texture_id, x, y));
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}
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}
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/* ground */
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else {
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if (dir.z < -0.4f) {
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xyz = make_float3(0.0f, 0.0f, 0.0f);
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}
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else {
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/* black ground fade */
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float fade = 1.0f + dir.z * 2.5f;
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fade = sqr(fade) * fade;
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/* interpolation */
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float x = (direction.y + M_PI_F + sun_rotation) / M_2PI_F;
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if (x > 1.0f) {
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x -= 1.0f;
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}
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xyz = float4_to_float3(kernel_tex_image_interp(kg, texture_id, x, -0.5)) * fade;
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}
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}
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/* convert to RGB */
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return xyz_to_rgb_clamped(kg, xyz);
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}
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ccl_device_noinline int svm_node_tex_sky(
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KernelGlobals kg, ccl_private ShaderData *sd, ccl_private float *stack, uint4 node, int offset)
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{
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/* Load data */
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uint dir_offset = node.y;
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uint out_offset = node.z;
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int sky_model = node.w;
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float3 dir = stack_load_float3(stack, dir_offset);
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float3 f;
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/* Preetham and Hosek share the same data */
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if (sky_model == 0 || sky_model == 1) {
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/* Define variables */
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float sunphi, suntheta, radiance_x, radiance_y, radiance_z;
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float config_x[9], config_y[9], config_z[9];
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float4 data = read_node_float(kg, &offset);
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sunphi = data.x;
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suntheta = data.y;
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radiance_x = data.z;
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radiance_y = data.w;
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data = read_node_float(kg, &offset);
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radiance_z = data.x;
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config_x[0] = data.y;
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config_x[1] = data.z;
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config_x[2] = data.w;
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data = read_node_float(kg, &offset);
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config_x[3] = data.x;
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config_x[4] = data.y;
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config_x[5] = data.z;
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config_x[6] = data.w;
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data = read_node_float(kg, &offset);
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config_x[7] = data.x;
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config_x[8] = data.y;
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config_y[0] = data.z;
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config_y[1] = data.w;
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data = read_node_float(kg, &offset);
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config_y[2] = data.x;
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config_y[3] = data.y;
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config_y[4] = data.z;
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config_y[5] = data.w;
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data = read_node_float(kg, &offset);
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config_y[6] = data.x;
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config_y[7] = data.y;
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config_y[8] = data.z;
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config_z[0] = data.w;
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data = read_node_float(kg, &offset);
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config_z[1] = data.x;
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config_z[2] = data.y;
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config_z[3] = data.z;
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config_z[4] = data.w;
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data = read_node_float(kg, &offset);
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config_z[5] = data.x;
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config_z[6] = data.y;
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config_z[7] = data.z;
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config_z[8] = data.w;
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/* Compute Sky */
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if (sky_model == 0) {
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f = sky_radiance_preetham(kg,
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dir,
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sunphi,
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suntheta,
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radiance_x,
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radiance_y,
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radiance_z,
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config_x,
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config_y,
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config_z);
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}
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else {
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f = sky_radiance_hosek(kg,
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dir,
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sunphi,
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suntheta,
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radiance_x,
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radiance_y,
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radiance_z,
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config_x,
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config_y,
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config_z);
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}
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}
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/* Nishita */
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else {
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/* Define variables */
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float nishita_data[4];
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float4 data = read_node_float(kg, &offset);
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float3 pixel_bottom = make_float3(data.x, data.y, data.z);
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float3 pixel_top;
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pixel_top.x = data.w;
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data = read_node_float(kg, &offset);
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pixel_top.y = data.x;
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pixel_top.z = data.y;
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nishita_data[0] = data.z;
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nishita_data[1] = data.w;
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data = read_node_float(kg, &offset);
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nishita_data[2] = data.x;
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nishita_data[3] = data.y;
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uint texture_id = __float_as_uint(data.z);
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/* Compute Sky */
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f = sky_radiance_nishita(kg, dir, pixel_bottom, pixel_top, nishita_data, texture_id);
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}
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stack_store_float3(stack, out_offset, f);
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return offset;
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}
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CCL_NAMESPACE_END
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