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out vec4 FragColor;
#ifdef VOLUMETRICS
uniform sampler2D depthFull;
void participating_media_properties(vec3 wpos, out vec3 absorption, out vec3 scattering, out float anisotropy)
{
Closure cl = nodetree_exec();
absorption = cl.absorption;
scattering = cl.scatter;
anisotropy = cl.anisotropy;
}
float phase_function_isotropic()
{
return 1.0 / (4.0 * M_PI);
}
float phase_function(vec3 v, vec3 l, float g)
{
#if 1
/* Henyey-Greenstein */
float cos_theta = dot(v, l);
float sqr_g = g * g;
return (1- sqr_g) / (4.0 * M_PI * pow(1 + sqr_g - 2 * g * cos_theta, 3.0 / 2.0));
#else
return phase_function_isotropic();
#endif
}
vec3 light_volume(LightData ld, vec4 l_vector, vec3 l_col)
{
float dist = max(1e-4, abs(l_vector.w - ld.l_radius));
return l_col * (4.0 * ld.l_radius * ld.l_radius * M_PI * M_PI) / (dist * dist);
}
float find_next_step(float near, float far, float noise, int iter, int iter_count)
{
const float lambda = 0.8f; /* TODO : Parameter */
float progress = (float(iter) + noise) / float(iter_count);
float linear_split = mix(near, far, progress);
if (ProjectionMatrix[3][3] == 0.0) {
float exp_split = near * pow(far / near, progress);
return mix(linear_split, exp_split, lambda);
}
else {
return linear_split;
}
}
/* Based on Frosbite Unified Volumetric.
* https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite */
void main()
{
vec2 uv = (gl_FragCoord.xy * 2.0) / ivec2(textureSize(depthFull, 0));
float scene_depth = texelFetch(depthFull, ivec2(gl_FragCoord.xy) * 2, 0).r; /* use the same depth as in the upsample step */
vec3 vpos = get_view_space_from_depth(uv, scene_depth);
vec3 wpos = (ViewMatrixInverse * vec4(vpos, 1.0)).xyz;
vec3 wdir = (ProjectionMatrix[3][3] == 0.0) ? normalize(cameraPos - wpos) : cameraForward;
/* Note: this is NOT the distance to the camera. */
float max_z = vpos.z;
/* project ray to clip plane so we can integrate in even steps in clip space. */
vec3 wdir_proj = wdir / abs(dot(cameraForward, wdir));
float wlen = length(wdir_proj);
/* Transmittance: How much light can get through. */
vec3 transmittance = vec3(1.0);
/* Scattering: Light that has been accumulated from scattered light sources. */
vec3 scattering = vec3(0.0);
vec3 ray_origin = (ProjectionMatrix[3][3] == 0.0)
? cameraPos
: (ViewMatrixInverse * vec4(get_view_space_from_depth(uv, 0.5), 1.0)).xyz;
/* Start from near clip. TODO make start distance an option. */
float rand = texture(utilTex, vec3(gl_FragCoord.xy / LUT_SIZE, 2.0)).r;
/* Less noisy but noticeable patterns, could work better with temporal AA. */
// float rand = (1.0 / 16.0) * float(((int(gl_FragCoord.x + gl_FragCoord.y) & 0x3) << 2) + (int(gl_FragCoord.x) & 0x3));
float near = get_view_z_from_depth(0.0);
float far = get_view_z_from_depth(1.0);
float dist = near;
for (int i = 1; i < 64; ++i) {
float new_dist = find_next_step(near, far, rand, i, 64);
float step = dist - new_dist; /* Marching step */
dist = new_dist;
vec3 ray_wpos = ray_origin + wdir_proj * dist;
/* Volume Sample */
vec3 s_absorption, s_scattering; /* mu_a, mu_s */
float s_anisotropy;
participating_media_properties(ray_wpos, s_absorption, s_scattering, s_anisotropy);
vec3 s_extinction = max(vec3(1e-8), s_absorption + s_scattering); /* mu_t */
/* Evaluate each light */
vec3 Lscat = vec3(0.0);
#if 1 /* Lights */
for (int i = 0; i < MAX_LIGHT && i < light_count; ++i) {
LightData ld = lights_data[i];
vec4 l_vector;
l_vector.xyz = ld.l_position - ray_wpos;
l_vector.w = length(l_vector.xyz);
#if 1 /* Shadows & Spots */
float Vis = light_visibility(ld, ray_wpos, l_vector);
#else
float Vis = 1.0;
#endif
vec3 Li = light_volume(ld, l_vector, ld.l_color);
Lscat += Li * Vis * s_scattering * phase_function(-wdir, l_vector.xyz / l_vector.w, s_anisotropy);
}
#endif
/* Environment : Average color. */
IrradianceData ir_data = load_irradiance_cell(0, vec3(1.0));
Lscat += (ir_data.cubesides[0] + ir_data.cubesides[1] + ir_data.cubesides[2]) * 0.333333 * s_scattering * phase_function_isotropic();
ir_data = load_irradiance_cell(0, vec3(-1.0));
Lscat += (ir_data.cubesides[0] + ir_data.cubesides[1] + ir_data.cubesides[2]) * 0.333333 * s_scattering * phase_function_isotropic();
/* Evaluate Scattering */
float s_len = wlen * step;
vec3 Tr = exp(-s_extinction * s_len);
/* integrate along the current step segment */
Lscat = (Lscat - Lscat * Tr) / s_extinction;
/* accumulate and also take into account the transmittance from previous steps */
scattering += transmittance * Lscat;
/* Evaluate transmittance to view independantely */
transmittance *= Tr;
if (dist < max_z)
break;
}
float mono_transmittance = dot(transmittance, vec3(1.0)) / 3.0;
FragColor = vec4(scattering, mono_transmittance);
}
#else /* STEP_UPSAMPLE */
uniform sampler2D depthFull;
uniform sampler2D volumetricBuffer;
uniform mat4 ProjectionMatrix;
vec4 get_view_z_from_depth(vec4 depth)
{
vec4 d = 2.0 * depth - 1.0;
return -ProjectionMatrix[3][2] / (d + ProjectionMatrix[2][2]);
}
void main()
{
#if 0 /* 2 x 2 with bilinear */
const vec4 bilinear_weights[4] = vec4[4](
vec4(9.0 / 16.0, 3.0 / 16.0, 3.0 / 16.0, 1.0 / 16.0 ),
vec4(3.0 / 16.0, 9.0 / 16.0, 1.0 / 16.0, 3.0 / 16.0 ),
vec4(3.0 / 16.0, 1.0 / 16.0, 9.0 / 16.0, 3.0 / 16.0 ),
vec4(1.0 / 16.0, 3.0 / 16.0, 3.0 / 16.0, 9.0 / 16.0 )
);
/* Depth aware upsampling */
vec4 depths;
ivec2 texel_co = ivec2(gl_FragCoord.xy * 0.5) * 2;
/* TODO use textureGather on glsl 4.0 */
depths.x = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 0)).r;
depths.y = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 0)).r;
depths.z = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 2)).r;
depths.w = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 2)).r;
vec4 target_depth = texelFetch(depthFull, ivec2(gl_FragCoord.xy), 0).rrrr;
depths = get_view_z_from_depth(depths);
target_depth = get_view_z_from_depth(target_depth);
vec4 weights = 1.0 - step(0.05, abs(depths - target_depth));
/* Index in range [0-3] */
int pix_id = int(dot(mod(ivec2(gl_FragCoord.xy), 2), ivec2(1, 2)));
weights *= bilinear_weights[pix_id];
float weight_sum = dot(weights, vec4(1.0));
if (weight_sum == 0.0) {
weights.x = 1.0;
weight_sum = 1.0;
}
texel_co = ivec2(gl_FragCoord.xy * 0.5);
vec4 integration_result;
integration_result = texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 0)) * weights.x;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 0)) * weights.y;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 1)) * weights.z;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 1)) * weights.w;
#else /* 4 x 4 */
/* Depth aware upsampling */
vec4 depths[4];
ivec2 texel_co = ivec2(gl_FragCoord.xy * 0.5) * 2;
/* TODO use textureGather on glsl 4.0 */
texel_co += ivec2(-2, -2);
depths[0].x = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 0)).r;
depths[0].y = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 0)).r;
depths[0].z = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 2)).r;
depths[0].w = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 2)).r;
texel_co += ivec2(4, 0);
depths[1].x = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 0)).r;
depths[1].y = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 0)).r;
depths[1].z = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 2)).r;
depths[1].w = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 2)).r;
texel_co += ivec2(-4, 4);
depths[2].x = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 0)).r;
depths[2].y = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 0)).r;
depths[2].z = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 2)).r;
depths[2].w = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 2)).r;
texel_co += ivec2(4, 0);
depths[3].x = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 0)).r;
depths[3].y = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 0)).r;
depths[3].z = texelFetchOffset(depthFull, texel_co, 0, ivec2(0, 2)).r;
depths[3].w = texelFetchOffset(depthFull, texel_co, 0, ivec2(2, 2)).r;
vec4 target_depth = texelFetch(depthFull, ivec2(gl_FragCoord.xy), 0).rrrr;
depths[0] = get_view_z_from_depth(depths[0]);
depths[1] = get_view_z_from_depth(depths[1]);
depths[2] = get_view_z_from_depth(depths[2]);
depths[3] = get_view_z_from_depth(depths[3]);
target_depth = get_view_z_from_depth(target_depth);
vec4 weights[4];
weights[0] = 1.0 - step(0.05, abs(depths[0] - target_depth));
weights[1] = 1.0 - step(0.05, abs(depths[1] - target_depth));
weights[2] = 1.0 - step(0.05, abs(depths[2] - target_depth));
weights[3] = 1.0 - step(0.05, abs(depths[3] - target_depth));
float weight_sum;
weight_sum = dot(weights[0], vec4(1.0));
weight_sum += dot(weights[1], vec4(1.0));
weight_sum += dot(weights[2], vec4(1.0));
weight_sum += dot(weights[3], vec4(1.0));
if (weight_sum == 0.0) {
weights[0].x = 1.0;
weight_sum = 1.0;
}
texel_co = ivec2(gl_FragCoord.xy * 0.5);
vec4 integration_result;
texel_co += ivec2(-1, -1);
integration_result = texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 0)) * weights[0].x;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 0)) * weights[0].y;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 1)) * weights[0].z;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 1)) * weights[0].w;
texel_co += ivec2(2, 0);
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 0)) * weights[1].x;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 0)) * weights[1].y;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 1)) * weights[1].z;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 1)) * weights[1].w;
texel_co += ivec2(-2, 2);
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 0)) * weights[2].x;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 0)) * weights[2].y;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 1)) * weights[2].z;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 1)) * weights[2].w;
texel_co += ivec2(2, 0);
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 0)) * weights[3].x;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 0)) * weights[3].y;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(0, 1)) * weights[3].z;
integration_result += texelFetchOffset(volumetricBuffer, texel_co, 0, ivec2(1, 1)) * weights[3].w;
#endif
FragColor = integration_result / weight_sum;
}
#endif
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