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Diffstat (limited to 'drivers/gles2/shaders/ssao.glsl')
| -rw-r--r-- | drivers/gles2/shaders/ssao.glsl | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/drivers/gles2/shaders/ssao.glsl b/drivers/gles2/shaders/ssao.glsl new file mode 100644 index 0000000000..0fd29e8dcc --- /dev/null +++ b/drivers/gles2/shaders/ssao.glsl @@ -0,0 +1,283 @@ +/* clang-format off */ +[vertex] + +layout(location = 0) in highp vec4 vertex_attrib; +/* clang-format on */ + +void main() { + gl_Position = vertex_attrib; + gl_Position.z = 1.0; +} + +/* clang-format off */ +[fragment] + +#define TWO_PI 6.283185307179586476925286766559 + +#ifdef SSAO_QUALITY_HIGH + +#define NUM_SAMPLES (80) + +#endif + +#ifdef SSAO_QUALITY_LOW + +#define NUM_SAMPLES (15) + +#endif + +#if !defined(SSAO_QUALITY_LOW) && !defined(SSAO_QUALITY_HIGH) + +#define NUM_SAMPLES (40) + +#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); +/* clang-format on */ + +//#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) { +#ifdef USE_ORTHOGONAL_PROJECTION + return vec3((S.xy * proj_info.xy + proj_info.zw), z); +#else + return vec3((S.xy * proj_info.xy + proj_info.zw) * z, z); + +#endif +} + +vec3 getPosition(ivec2 ssP) { + vec3 P; + P.z = texelFetch(source_depth, ssP, 0).r; + + P.z = P.z * 2.0 - 1.0; +#ifdef USE_ORTHOGONAL_PROJECTION + P.z = ((P.z + (camera_z_far + camera_z_near) / (camera_z_far - camera_z_near)) * (camera_z_far - camera_z_near)) / 2.0; +#else + P.z = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - P.z * (camera_z_far - camera_z_near)); +#endif + 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; +#ifdef USE_ORTHOGONAL_PROJECTION + P.z = ((P.z + (camera_z_far + camera_z_near) / (camera_z_far - camera_z_near)) * (camera_z_far - camera_z_near)) / 2.0; +#else + P.z = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - P.z * (camera_z_far - camera_z_near)); + +#endif + 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; +#if 0 + vec3 n_C = texelFetch(source_normal,ssC,0).rgb * 2.0 - 1.0; +#else + vec3 n_C = reconstructCSFaceNormal(C); + n_C = -n_C; +#endif + + // 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 +#ifdef USE_ORTHOGONAL_PROJECTION + float ssDiskRadius = -proj_scale * radius; +#else + float ssDiskRadius = -proj_scale * radius / C.z; +#endif + 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 = mod(float((5 * ssC.x ^ ssC.y + ssC.x * ssC.y) * 11), 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 + 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; +} |