260 lines
7.9 KiB
GLSL
260 lines
7.9 KiB
GLSL
[vertex]
|
|
|
|
|
|
layout(location=0) in highp vec4 vertex_attrib;
|
|
|
|
void main() {
|
|
|
|
gl_Position = vertex_attrib;
|
|
gl_Position.z=1.0;
|
|
}
|
|
|
|
[fragment]
|
|
|
|
|
|
#define NUM_SAMPLES (15)
|
|
|
|
// 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];
|
|
|
|
uniform sampler2D source_depth; //texunit:0
|
|
uniform highp usampler2D source_depth_mipmaps; //texunit:1
|
|
uniform sampler2D source_normal; //texunit:2
|
|
|
|
uniform ivec2 screen_size;
|
|
uniform float camera_z_far;
|
|
uniform float camera_z_near;
|
|
|
|
uniform float intensity_div_r6;
|
|
uniform float radius;
|
|
|
|
#ifdef ENABLE_RADIUS2
|
|
uniform float intensity_div_r62;
|
|
uniform float radius2;
|
|
#endif
|
|
|
|
uniform float bias;
|
|
uniform float proj_scale;
|
|
|
|
layout(location = 0) out float visibility;
|
|
|
|
uniform vec4 proj_info;
|
|
|
|
vec3 reconstructCSPosition(vec2 S, float z) {
|
|
return vec3((S.xy * proj_info.xy + proj_info.zw) * z, z);
|
|
}
|
|
|
|
vec3 getPosition(ivec2 ssP) {
|
|
vec3 P;
|
|
P.z = texelFetch(source_depth, ssP, 0).r;
|
|
|
|
P.z = P.z * 2.0 - 1.0;
|
|
P.z = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - P.z * (camera_z_far - camera_z_near));
|
|
P.z = -P.z;
|
|
|
|
// Offset to pixel center
|
|
P = reconstructCSPosition(vec2(ssP) + vec2(0.5), P.z);
|
|
return P;
|
|
}
|
|
|
|
/** Reconstructs screen-space unit normal from screen-space position */
|
|
vec3 reconstructCSFaceNormal(vec3 C) {
|
|
return normalize(cross(dFdy(C), dFdx(C)));
|
|
}
|
|
|
|
|
|
|
|
/** 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 ssC, vec2 unitOffset, float ssR) {
|
|
// Derivation:
|
|
// mipLevel = floor(log(ssR / MAX_OFFSET));
|
|
int mipLevel = clamp(int(floor(log2(ssR))) - LOG_MAX_OFFSET, 0, MAX_MIP_LEVEL);
|
|
|
|
ivec2 ssP = ivec2(ssR * unitOffset) + ssC;
|
|
|
|
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), (screen_size >> mipLevel) - ivec2(1));
|
|
|
|
|
|
if (mipLevel < 1) {
|
|
//read from depth buffer
|
|
P.z = texelFetch(source_depth, mipP, 0).r;
|
|
P.z = P.z * 2.0 - 1.0;
|
|
P.z = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - P.z * (camera_z_far - camera_z_near));
|
|
P.z = -P.z;
|
|
|
|
} else {
|
|
//read from mipmaps
|
|
uint d = texelFetch(source_depth_mipmaps, mipP, mipLevel-1).r;
|
|
P.z = -(float(d)/65535.0)*camera_z_far;
|
|
}
|
|
|
|
|
|
// 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;
|
|
|
|
// The occluding point in camera space
|
|
vec3 Q = getOffsetPosition(ssC, unitOffset, 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 - 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_FragCoord.xy);
|
|
|
|
// World space point being shaded
|
|
vec3 C = getPosition(ssC);
|
|
|
|
/* if (C.z <= -camera_z_far*0.999) {
|
|
// We're on the skybox
|
|
visibility=1.0;
|
|
return;
|
|
}*/
|
|
|
|
//visibility=-C.z/camera_z_far;
|
|
//return;
|
|
|
|
//vec3 n_C = texelFetch(source_normal,ssC,0).rgb * 2.0 - 1.0;
|
|
|
|
vec3 n_C = reconstructCSFaceNormal(C);
|
|
n_C = -n_C;
|
|
|
|
|
|
// Hash function used in the HPG12 AlchemyAO paper
|
|
float randomPatternRotationAngle = float((3 * ssC.x ^ ssC.y + ssC.x * ssC.y) * 10);
|
|
|
|
// 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 = -proj_scale * radius / C.z;
|
|
|
|
float sum = 0.0;
|
|
for (int i = 0; i < NUM_SAMPLES; ++i) {
|
|
sum += sampleAO(ssC, C, n_C, ssDiskRadius, radius,i, randomPatternRotationAngle);
|
|
}
|
|
|
|
float A = max(0.0, 1.0 - sum * intensity_div_r6 * (5.0 / float(NUM_SAMPLES)));
|
|
|
|
#ifdef ENABLE_RADIUS2
|
|
|
|
//go again for radius2
|
|
randomPatternRotationAngle = float((5 * ssC.x ^ ssC.y + ssC.x * ssC.y) * 11);
|
|
|
|
// 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
|
|
ssDiskRadius = -proj_scale * radius2 / C.z;
|
|
|
|
sum = 0.0;
|
|
for (int i = 0; i < NUM_SAMPLES; ++i) {
|
|
sum += sampleAO(ssC, C, n_C, ssDiskRadius,radius2, i, randomPatternRotationAngle);
|
|
}
|
|
|
|
A= min(A,max(0.0, 1.0 - sum * intensity_div_r62 * (5.0 / float(NUM_SAMPLES))));
|
|
#endif
|
|
// Bilateral box-filter over a quad for free, respecting depth edges
|
|
// (the difference that this makes is subtle)
|
|
if (abs(dFdx(C.z)) < 0.02) {
|
|
A -= dFdx(A) * (float(ssC.x & 1) - 0.5);
|
|
}
|
|
if (abs(dFdy(C.z)) < 0.02) {
|
|
A -= dFdy(A) * (float(ssC.y & 1) - 0.5);
|
|
}
|
|
|
|
visibility = A;
|
|
|
|
}
|
|
|
|
|
|
|