4226d56ca9
As of clang-format 6.0.1, putting the `/* clang-format off */` hint around our "invalid" `[vertex]` and `[shader]` statements isn't enough to prevent a bogus indent of the next comments and first valid statement, so we need to enclose that first valid statement in the unformatted chunk.
285 lines
8.7 KiB
GLSL
285 lines
8.7 KiB
GLSL
/* clang-format off */
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[vertex]
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layout(location = 0) in highp vec4 vertex_attrib;
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/* clang-format on */
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void main() {
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gl_Position = vertex_attrib;
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gl_Position.z = 1.0;
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}
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/* clang-format off */
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[fragment]
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#define TWO_PI 6.283185307179586476925286766559
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#ifdef SSAO_QUALITY_HIGH
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#define NUM_SAMPLES (80)
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#endif
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#ifdef SSAO_QUALITY_LOW
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#define NUM_SAMPLES (15)
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#endif
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#if !defined(SSAO_QUALITY_LOW) && !defined(SSAO_QUALITY_HIGH)
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#define NUM_SAMPLES (40)
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#endif
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// If using depth mip levels, the log of the maximum pixel offset before we need to switch to a lower
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// miplevel to maintain reasonable spatial locality in the cache
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// 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.
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// If it is too high (> 5), we'll get bad performance because we're not using the MIP levels effectively
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#define LOG_MAX_OFFSET (3)
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// This must be less than or equal to the MAX_MIP_LEVEL defined in SSAO.cpp
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#define MAX_MIP_LEVEL (4)
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// This is the number of turns around the circle that the spiral pattern makes. This should be prime to prevent
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// taps from lining up. This particular choice was tuned for NUM_SAMPLES == 9
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const int ROTATIONS[] = int[](
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1, 1, 2, 3, 2, 5, 2, 3, 2,
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3, 3, 5, 5, 3, 4, 7, 5, 5, 7,
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9, 8, 5, 5, 7, 7, 7, 8, 5, 8,
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11, 12, 7, 10, 13, 8, 11, 8, 7, 14,
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11, 11, 13, 12, 13, 19, 17, 13, 11, 18,
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19, 11, 11, 14, 17, 21, 15, 16, 17, 18,
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13, 17, 11, 17, 19, 18, 25, 18, 19, 19,
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29, 21, 19, 27, 31, 29, 21, 18, 17, 29,
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31, 31, 23, 18, 25, 26, 25, 23, 19, 34,
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19, 27, 21, 25, 39, 29, 17, 21, 27);
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/* clang-format on */
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//#define NUM_SPIRAL_TURNS (7)
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const int NUM_SPIRAL_TURNS = ROTATIONS[NUM_SAMPLES - 1];
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uniform sampler2D source_depth; //texunit:0
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uniform highp usampler2D source_depth_mipmaps; //texunit:1
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uniform sampler2D source_normal; //texunit:2
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uniform ivec2 screen_size;
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uniform float camera_z_far;
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uniform float camera_z_near;
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uniform float intensity_div_r6;
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uniform float radius;
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#ifdef ENABLE_RADIUS2
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uniform float intensity_div_r62;
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uniform float radius2;
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#endif
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uniform float bias;
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uniform float proj_scale;
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layout(location = 0) out float visibility;
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uniform vec4 proj_info;
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vec3 reconstructCSPosition(vec2 S, float z) {
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#ifdef USE_ORTHOGONAL_PROJECTION
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return vec3((S.xy * proj_info.xy + proj_info.zw), z);
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#else
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return vec3((S.xy * proj_info.xy + proj_info.zw) * z, z);
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#endif
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}
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vec3 getPosition(ivec2 ssP) {
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vec3 P;
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P.z = texelFetch(source_depth, ssP, 0).r;
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P.z = P.z * 2.0 - 1.0;
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#ifdef USE_ORTHOGONAL_PROJECTION
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P.z = ((P.z + (camera_z_far + camera_z_near) / (camera_z_far - camera_z_near)) * (camera_z_far - camera_z_near)) / 2.0;
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#else
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P.z = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - P.z * (camera_z_far - camera_z_near));
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#endif
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P.z = -P.z;
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// Offset to pixel center
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P = reconstructCSPosition(vec2(ssP) + vec2(0.5), P.z);
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return P;
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}
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/** Reconstructs screen-space unit normal from screen-space position */
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vec3 reconstructCSFaceNormal(vec3 C) {
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return normalize(cross(dFdy(C), dFdx(C)));
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}
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/** 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) */
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vec2 tapLocation(int sampleNumber, float spinAngle, out float ssR) {
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// Radius relative to ssR
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float alpha = (float(sampleNumber) + 0.5) * (1.0 / float(NUM_SAMPLES));
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float angle = alpha * (float(NUM_SPIRAL_TURNS) * 6.28) + spinAngle;
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ssR = alpha;
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return vec2(cos(angle), sin(angle));
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}
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/** Read the camera-space position of the point at screen-space pixel ssP + unitOffset * ssR. Assumes length(unitOffset) == 1 */
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vec3 getOffsetPosition(ivec2 ssC, vec2 unitOffset, float ssR) {
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// Derivation:
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// mipLevel = floor(log(ssR / MAX_OFFSET));
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int mipLevel = clamp(int(floor(log2(ssR))) - LOG_MAX_OFFSET, 0, MAX_MIP_LEVEL);
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ivec2 ssP = ivec2(ssR * unitOffset) + ssC;
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vec3 P;
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// We need to divide by 2^mipLevel to read the appropriately scaled coordinate from a MIP-map.
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// Manually clamp to the texture size because texelFetch bypasses the texture unit
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ivec2 mipP = clamp(ssP >> mipLevel, ivec2(0), (screen_size >> mipLevel) - ivec2(1));
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if (mipLevel < 1) {
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//read from depth buffer
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P.z = texelFetch(source_depth, mipP, 0).r;
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P.z = P.z * 2.0 - 1.0;
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#ifdef USE_ORTHOGONAL_PROJECTION
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P.z = ((P.z + (camera_z_far + camera_z_near) / (camera_z_far - camera_z_near)) * (camera_z_far - camera_z_near)) / 2.0;
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#else
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P.z = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - P.z * (camera_z_far - camera_z_near));
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#endif
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P.z = -P.z;
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} else {
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//read from mipmaps
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uint d = texelFetch(source_depth_mipmaps, mipP, mipLevel - 1).r;
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P.z = -(float(d) / 65535.0) * camera_z_far;
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}
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// Offset to pixel center
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P = reconstructCSPosition(vec2(ssP) + vec2(0.5), P.z);
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return P;
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}
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/** Compute the occlusion due to sample with index \a i about the pixel at \a ssC that corresponds
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to camera-space point \a C with unit normal \a n_C, using maximum screen-space sampling radius \a ssDiskRadius
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Note that units of H() in the HPG12 paper are meters, not
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unitless. The whole falloff/sampling function is therefore
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unitless. In this implementation, we factor out (9 / radius).
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Four versions of the falloff function are implemented below
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*/
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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) {
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// Offset on the unit disk, spun for this pixel
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float ssR;
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vec2 unitOffset = tapLocation(tapIndex, randomPatternRotationAngle, ssR);
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ssR *= ssDiskRadius;
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// The occluding point in camera space
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vec3 Q = getOffsetPosition(ssC, unitOffset, ssR);
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vec3 v = Q - C;
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float vv = dot(v, v);
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float vn = dot(v, n_C);
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const float epsilon = 0.01;
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float radius2 = p_radius * p_radius;
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// A: From the HPG12 paper
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// Note large epsilon to avoid overdarkening within cracks
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//return float(vv < radius2) * max((vn - bias) / (epsilon + vv), 0.0) * radius2 * 0.6;
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// B: Smoother transition to zero (lowers contrast, smoothing out corners). [Recommended]
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float f = max(radius2 - vv, 0.0);
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return f * f * f * max((vn - bias) / (epsilon + vv), 0.0);
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// C: Medium contrast (which looks better at high radii), no division. Note that the
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// contribution still falls off with radius^2, but we've adjusted the rate in a way that is
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// more computationally efficient and happens to be aesthetically pleasing.
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// return 4.0 * max(1.0 - vv * invRadius2, 0.0) * max(vn - bias, 0.0);
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// D: Low contrast, no division operation
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// return 2.0 * float(vv < radius * radius) * max(vn - bias, 0.0);
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}
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void main() {
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// Pixel being shaded
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ivec2 ssC = ivec2(gl_FragCoord.xy);
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// World space point being shaded
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vec3 C = getPosition(ssC);
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/*
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if (C.z <= -camera_z_far*0.999) {
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// We're on the skybox
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visibility=1.0;
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return;
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}
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*/
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//visibility=-C.z/camera_z_far;
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//return;
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#if 0
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vec3 n_C = texelFetch(source_normal,ssC,0).rgb * 2.0 - 1.0;
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#else
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vec3 n_C = reconstructCSFaceNormal(C);
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n_C = -n_C;
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#endif
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// Hash function used in the HPG12 AlchemyAO paper
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float randomPatternRotationAngle = mod(float((3 * ssC.x ^ ssC.y + ssC.x * ssC.y) * 10), TWO_PI);
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// Reconstruct normals from positions. These will lead to 1-pixel black lines
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// at depth discontinuities, however the blur will wipe those out so they are not visible
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// in the final image.
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// Choose the screen-space sample radius
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// proportional to the projected area of the sphere
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#ifdef USE_ORTHOGONAL_PROJECTION
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float ssDiskRadius = -proj_scale * radius;
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#else
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float ssDiskRadius = -proj_scale * radius / C.z;
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#endif
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float sum = 0.0;
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for (int i = 0; i < NUM_SAMPLES; ++i) {
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sum += sampleAO(ssC, C, n_C, ssDiskRadius, radius, i, randomPatternRotationAngle);
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}
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float A = max(0.0, 1.0 - sum * intensity_div_r6 * (5.0 / float(NUM_SAMPLES)));
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#ifdef ENABLE_RADIUS2
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//go again for radius2
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randomPatternRotationAngle = mod(float((5 * ssC.x ^ ssC.y + ssC.x * ssC.y) * 11), TWO_PI);
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// Reconstruct normals from positions. These will lead to 1-pixel black lines
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// at depth discontinuities, however the blur will wipe those out so they are not visible
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// in the final image.
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// Choose the screen-space sample radius
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// proportional to the projected area of the sphere
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ssDiskRadius = -proj_scale * radius2 / C.z;
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sum = 0.0;
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for (int i = 0; i < NUM_SAMPLES; ++i) {
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sum += sampleAO(ssC, C, n_C, ssDiskRadius, radius2, i, randomPatternRotationAngle);
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}
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A = min(A, max(0.0, 1.0 - sum * intensity_div_r62 * (5.0 / float(NUM_SAMPLES))));
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#endif
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// Bilateral box-filter over a quad for free, respecting depth edges
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// (the difference that this makes is subtle)
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if (abs(dFdx(C.z)) < 0.02) {
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A -= dFdx(A) * (float(ssC.x & 1) - 0.5);
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}
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if (abs(dFdy(C.z)) < 0.02) {
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A -= dFdy(A) * (float(ssC.y & 1) - 0.5);
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}
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visibility = A;
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}
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