virtualx-engine/servers/rendering/renderer_rd/shaders/ssao.glsl
2020-12-04 18:39:46 -03:00

249 lines
8 KiB
GLSL

#[compute]
#version 450
VERSION_DEFINES
layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
#define TWO_PI 6.283185307179586476925286766559
#ifdef SSAO_QUALITY_HIGH
#define NUM_SAMPLES (20)
#endif
#ifdef SSAO_QUALITY_ULTRA
#define NUM_SAMPLES (48)
#endif
#ifdef SSAO_QUALITY_LOW
#define NUM_SAMPLES (8)
#endif
#if !defined(SSAO_QUALITY_LOW) && !defined(SSAO_QUALITY_HIGH) && !defined(SSAO_QUALITY_ULTRA)
#define NUM_SAMPLES (12)
#endif
// If using depth mip levels, the log of the maximum pixel offset before we need to switch to a lower
// miplevel to maintain reasonable spatial locality in the cache
// If this number is too small (< 3), too many taps will land in the same pixel, and we'll get bad variance that manifests as flashing.
// If it is too high (> 5), we'll get bad performance because we're not using the MIP levels effectively
#define LOG_MAX_OFFSET (3)
// This must be less than or equal to the MAX_MIP_LEVEL defined in SSAO.cpp
#define MAX_MIP_LEVEL (4)
// This is the number of turns around the circle that the spiral pattern makes. This should be prime to prevent
// taps from lining up. This particular choice was tuned for NUM_SAMPLES == 9
const int ROTATIONS[] = int[](
1, 1, 2, 3, 2, 5, 2, 3, 2,
3, 3, 5, 5, 3, 4, 7, 5, 5, 7,
9, 8, 5, 5, 7, 7, 7, 8, 5, 8,
11, 12, 7, 10, 13, 8, 11, 8, 7, 14,
11, 11, 13, 12, 13, 19, 17, 13, 11, 18,
19, 11, 11, 14, 17, 21, 15, 16, 17, 18,
13, 17, 11, 17, 19, 18, 25, 18, 19, 19,
29, 21, 19, 27, 31, 29, 21, 18, 17, 29,
31, 31, 23, 18, 25, 26, 25, 23, 19, 34,
19, 27, 21, 25, 39, 29, 17, 21, 27);
//#define NUM_SPIRAL_TURNS (7)
const int NUM_SPIRAL_TURNS = ROTATIONS[NUM_SAMPLES - 1];
layout(set = 0, binding = 0) uniform sampler2D source_depth_mipmaps;
layout(r8, set = 1, binding = 0) uniform restrict writeonly image2D dest_image;
#ifndef USE_HALF_SIZE
layout(set = 2, binding = 0) uniform sampler2D source_depth;
#endif
layout(set = 3, binding = 0) uniform sampler2D source_normal;
layout(push_constant, binding = 1, std430) uniform Params {
ivec2 screen_size;
float z_far;
float z_near;
bool orthogonal;
float intensity_div_r6;
float radius;
float bias;
vec4 proj_info;
vec2 pixel_size;
float proj_scale;
uint pad;
}
params;
vec3 reconstructCSPosition(vec2 S, float z) {
if (params.orthogonal) {
return vec3((S.xy * params.proj_info.xy + params.proj_info.zw), z);
} else {
return vec3((S.xy * params.proj_info.xy + params.proj_info.zw) * z, z);
}
}
vec3 getPosition(ivec2 ssP) {
vec3 P;
#ifdef USE_HALF_SIZE
P.z = texelFetch(source_depth_mipmaps, ssP, 0).r;
P.z = -P.z;
#else
P.z = texelFetch(source_depth, ssP, 0).r;
P.z = P.z * 2.0 - 1.0;
if (params.orthogonal) {
P.z = ((P.z + (params.z_far + params.z_near) / (params.z_far - params.z_near)) * (params.z_far - params.z_near)) / 2.0;
} else {
P.z = 2.0 * params.z_near * params.z_far / (params.z_far + params.z_near - P.z * (params.z_far - params.z_near));
}
P.z = -P.z;
#endif
// Offset to pixel center
P = reconstructCSPosition(vec2(ssP) + vec2(0.5), P.z);
return P;
}
/** Returns a unit vector and a screen-space radius for the tap on a unit disk (the caller should scale by the actual disk radius) */
vec2 tapLocation(int sampleNumber, float spinAngle, out float ssR) {
// Radius relative to ssR
float alpha = (float(sampleNumber) + 0.5) * (1.0 / float(NUM_SAMPLES));
float angle = alpha * (float(NUM_SPIRAL_TURNS) * 6.28) + spinAngle;
ssR = alpha;
return vec2(cos(angle), sin(angle));
}
/** Read the camera-space position of the point at screen-space pixel ssP + unitOffset * ssR. Assumes length(unitOffset) == 1 */
vec3 getOffsetPosition(ivec2 ssP, float ssR) {
// Derivation:
// mipLevel = floor(log(ssR / MAX_OFFSET));
int mipLevel = clamp(int(floor(log2(ssR))) - LOG_MAX_OFFSET, 0, MAX_MIP_LEVEL);
vec3 P;
// We need to divide by 2^mipLevel to read the appropriately scaled coordinate from a MIP-map.
// Manually clamp to the texture size because texelFetch bypasses the texture unit
ivec2 mipP = clamp(ssP >> mipLevel, ivec2(0), (params.screen_size >> mipLevel) - ivec2(1));
#ifdef USE_HALF_SIZE
P.z = texelFetch(source_depth_mipmaps, mipP, mipLevel).r;
P.z = -P.z;
#else
if (mipLevel < 1) {
//read from depth buffer
P.z = texelFetch(source_depth, mipP, 0).r;
P.z = P.z * 2.0 - 1.0;
if (params.orthogonal) {
P.z = ((P.z + (params.z_far + params.z_near) / (params.z_far - params.z_near)) * (params.z_far - params.z_near)) / 2.0;
} else {
P.z = 2.0 * params.z_near * params.z_far / (params.z_far + params.z_near - P.z * (params.z_far - params.z_near));
}
P.z = -P.z;
} else {
//read from mipmaps
P.z = texelFetch(source_depth_mipmaps, mipP, mipLevel - 1).r;
P.z = -P.z;
}
#endif
// Offset to pixel center
P = reconstructCSPosition(vec2(ssP) + vec2(0.5), P.z);
return P;
}
/** Compute the occlusion due to sample with index \a i about the pixel at \a ssC that corresponds
to camera-space point \a C with unit normal \a n_C, using maximum screen-space sampling radius \a ssDiskRadius
Note that units of H() in the HPG12 paper are meters, not
unitless. The whole falloff/sampling function is therefore
unitless. In this implementation, we factor out (9 / radius).
Four versions of the falloff function are implemented below
*/
float sampleAO(in ivec2 ssC, in vec3 C, in vec3 n_C, in float ssDiskRadius, in float p_radius, in int tapIndex, in float randomPatternRotationAngle) {
// Offset on the unit disk, spun for this pixel
float ssR;
vec2 unitOffset = tapLocation(tapIndex, randomPatternRotationAngle, ssR);
ssR *= ssDiskRadius;
ivec2 ssP = ivec2(ssR * unitOffset) + ssC;
if (any(lessThan(ssP, ivec2(0))) || any(greaterThanEqual(ssP, params.screen_size))) {
return 0.0;
}
// The occluding point in camera space
vec3 Q = getOffsetPosition(ssP, ssR);
vec3 v = Q - C;
float vv = dot(v, v);
float vn = dot(v, n_C);
const float epsilon = 0.01;
float radius2 = p_radius * p_radius;
// A: From the HPG12 paper
// Note large epsilon to avoid overdarkening within cracks
//return float(vv < radius2) * max((vn - bias) / (epsilon + vv), 0.0) * radius2 * 0.6;
// B: Smoother transition to zero (lowers contrast, smoothing out corners). [Recommended]
float f = max(radius2 - vv, 0.0);
return f * f * f * max((vn - params.bias) / (epsilon + vv), 0.0);
// C: Medium contrast (which looks better at high radii), no division. Note that the
// contribution still falls off with radius^2, but we've adjusted the rate in a way that is
// more computationally efficient and happens to be aesthetically pleasing.
// return 4.0 * max(1.0 - vv * invRadius2, 0.0) * max(vn - bias, 0.0);
// D: Low contrast, no division operation
// return 2.0 * float(vv < radius * radius) * max(vn - bias, 0.0);
}
void main() {
// Pixel being shaded
ivec2 ssC = ivec2(gl_GlobalInvocationID.xy);
if (any(greaterThanEqual(ssC, params.screen_size))) { //too large, do nothing
return;
}
// World space point being shaded
vec3 C = getPosition(ssC);
#ifdef USE_HALF_SIZE
vec3 n_C = texelFetch(source_normal, ssC << 1, 0).xyz * 2.0 - 1.0;
#else
vec3 n_C = texelFetch(source_normal, ssC, 0).xyz * 2.0 - 1.0;
#endif
n_C = normalize(n_C);
n_C.y = -n_C.y; //because this code reads flipped
// Hash function used in the HPG12 AlchemyAO paper
float randomPatternRotationAngle = mod(float((3 * ssC.x ^ ssC.y + ssC.x * ssC.y) * 10), TWO_PI);
// Reconstruct normals from positions. These will lead to 1-pixel black lines
// at depth discontinuities, however the blur will wipe those out so they are not visible
// in the final image.
// Choose the screen-space sample radius
// proportional to the projected area of the sphere
float ssDiskRadius = -params.proj_scale * params.radius;
if (!params.orthogonal) {
ssDiskRadius = -params.proj_scale * params.radius / C.z;
}
float sum = 0.0;
for (int i = 0; i < NUM_SAMPLES; ++i) {
sum += sampleAO(ssC, C, n_C, ssDiskRadius, params.radius, i, randomPatternRotationAngle);
}
float A = max(0.0, 1.0 - sum * params.intensity_div_r6 * (5.0 / float(NUM_SAMPLES)));
imageStore(dest_image, ssC, vec4(A));
}