| /* |
| * Copyright 2018 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #pragma once |
| |
| #include <GLES3/gl3.h> |
| #include <math/vec2.h> |
| #include <math/vec3.h> |
| #include <math/vec4.h> |
| |
| static const char* VERTEX_SHADER = R"SHADER__(#version 300 es |
| precision highp float; |
| |
| layout(location = 0) in vec4 mesh_position; |
| |
| void main() { |
| gl_Position = mesh_position; |
| } |
| )SHADER__"; |
| |
| static const char* FRAGMENT_SHADER = R"SHADER__(#version 300 es |
| precision highp float; |
| |
| layout(location = 0) uniform vec4 resolution; |
| layout(location = 1) uniform float time; |
| layout(location = 2) uniform vec3[4] SPHERICAL_HARMONICS; |
| |
| layout(location = 0) out vec4 fragColor; |
| |
| #define saturate(x) clamp(x, 0.0, 1.0) |
| #define PI 3.14159265359 |
| |
| //------------------------------------------------------------------------------ |
| // Distance field functions |
| //------------------------------------------------------------------------------ |
| |
| float sdPlane(in vec3 p) { |
| return p.y; |
| } |
| |
| float sdSphere(in vec3 p, float s) { |
| return length(p) - s; |
| } |
| |
| float sdTorus(in vec3 p, in vec2 t) { |
| return length(vec2(length(p.xz) - t.x, p.y)) - t.y; |
| } |
| |
| vec2 opUnion(vec2 d1, vec2 d2) { |
| return d1.x < d2.x ? d1 : d2; |
| } |
| |
| vec2 scene(in vec3 position) { |
| vec2 scene = opUnion( |
| vec2(sdPlane(position), 1.0), |
| vec2(sdSphere(position - vec3(0.0, 0.4, 0.0), 0.4), 12.0) |
| ); |
| return scene; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Ray casting |
| //------------------------------------------------------------------------------ |
| |
| float shadow(in vec3 origin, in vec3 direction, in float tmin, in float tmax) { |
| float hit = 1.0; |
| |
| for (float t = tmin; t < tmax; ) { |
| float h = scene(origin + direction * t).x; |
| if (h < 0.001) return 0.0; |
| t += h; |
| hit = min(hit, 10.0 * h / t); |
| } |
| |
| return clamp(hit, 0.0, 1.0); |
| } |
| |
| vec2 traceRay(in vec3 origin, in vec3 direction) { |
| float tmin = 0.02; |
| float tmax = 20.0; |
| |
| float material = -1.0; |
| float t = tmin; |
| |
| for ( ; t < tmax; ) { |
| vec2 hit = scene(origin + direction * t); |
| if (hit.x < 0.002 || t > tmax) break; |
| t += hit.x; |
| material = hit.y; |
| } |
| |
| if (t > tmax) { |
| material = -1.0; |
| } |
| |
| return vec2(t, material); |
| } |
| |
| vec3 normal(in vec3 position) { |
| vec3 epsilon = vec3(0.001, 0.0, 0.0); |
| vec3 n = vec3( |
| scene(position + epsilon.xyy).x - scene(position - epsilon.xyy).x, |
| scene(position + epsilon.yxy).x - scene(position - epsilon.yxy).x, |
| scene(position + epsilon.yyx).x - scene(position - epsilon.yyx).x); |
| return normalize(n); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // BRDF |
| //------------------------------------------------------------------------------ |
| |
| float pow5(float x) { |
| float x2 = x * x; |
| return x2 * x2 * x; |
| } |
| |
| float D_GGX(float linearRoughness, float NoH, const vec3 h) { |
| // Walter et al. 2007, "Microfacet Models for Refraction through Rough Surfaces" |
| float oneMinusNoHSquared = 1.0 - NoH * NoH; |
| float a = NoH * linearRoughness; |
| float k = linearRoughness / (oneMinusNoHSquared + a * a); |
| float d = k * k * (1.0 / PI); |
| return d; |
| } |
| |
| float V_SmithGGXCorrelated(float linearRoughness, float NoV, float NoL) { |
| // Heitz 2014, "Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs" |
| float a2 = linearRoughness * linearRoughness; |
| float GGXV = NoL * sqrt((NoV - a2 * NoV) * NoV + a2); |
| float GGXL = NoV * sqrt((NoL - a2 * NoL) * NoL + a2); |
| return 0.5 / (GGXV + GGXL); |
| } |
| |
| vec3 F_Schlick(const vec3 f0, float VoH) { |
| // Schlick 1994, "An Inexpensive BRDF Model for Physically-Based Rendering" |
| return f0 + (vec3(1.0) - f0) * pow5(1.0 - VoH); |
| } |
| |
| float F_Schlick(float f0, float f90, float VoH) { |
| return f0 + (f90 - f0) * pow5(1.0 - VoH); |
| } |
| |
| float Fd_Burley(float linearRoughness, float NoV, float NoL, float LoH) { |
| // Burley 2012, "Physically-Based Shading at Disney" |
| float f90 = 0.5 + 2.0 * linearRoughness * LoH * LoH; |
| float lightScatter = F_Schlick(1.0, f90, NoL); |
| float viewScatter = F_Schlick(1.0, f90, NoV); |
| return lightScatter * viewScatter * (1.0 / PI); |
| } |
| |
| float Fd_Lambert() { |
| return 1.0 / PI; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Indirect lighting |
| //------------------------------------------------------------------------------ |
| |
| vec3 Irradiance_SphericalHarmonics(const vec3 n) { |
| return max( |
| SPHERICAL_HARMONICS[0] |
| + SPHERICAL_HARMONICS[1] * (n.y) |
| + SPHERICAL_HARMONICS[2] * (n.z) |
| + SPHERICAL_HARMONICS[3] * (n.x) |
| , 0.0); |
| } |
| |
| vec2 PrefilteredDFG_Karis(float roughness, float NoV) { |
| // Karis 2014, "Physically Based Material on Mobile" |
| const vec4 c0 = vec4(-1.0, -0.0275, -0.572, 0.022); |
| const vec4 c1 = vec4( 1.0, 0.0425, 1.040, -0.040); |
| |
| vec4 r = roughness * c0 + c1; |
| float a004 = min(r.x * r.x, exp2(-9.28 * NoV)) * r.x + r.y; |
| |
| return vec2(-1.04, 1.04) * a004 + r.zw; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Tone mapping and transfer functions |
| //------------------------------------------------------------------------------ |
| |
| vec3 Tonemap_ACES(const vec3 x) { |
| // Narkowicz 2015, "ACES Filmic Tone Mapping Curve" |
| const float a = 2.51; |
| const float b = 0.03; |
| const float c = 2.43; |
| const float d = 0.59; |
| const float e = 0.14; |
| return (x * (a * x + b)) / (x * (c * x + d) + e); |
| } |
| |
| vec3 OECF_sRGBFast(const vec3 linear) { |
| return pow(linear, vec3(1.0 / 2.2)); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Rendering |
| //------------------------------------------------------------------------------ |
| |
| vec3 render(in vec3 origin, in vec3 direction, out float distance) { |
| // Sky gradient |
| vec3 color = vec3(0.65, 0.85, 1.0) + direction.y * 0.72; |
| |
| // (distance, material) |
| vec2 hit = traceRay(origin, direction); |
| distance = hit.x; |
| float material = hit.y; |
| |
| // We've hit something in the scene |
| if (material > 0.0) { |
| vec3 position = origin + distance * direction; |
| |
| vec3 v = normalize(-direction); |
| vec3 n = normal(position); |
| vec3 l = normalize(vec3(0.6, 0.7, -0.7)); |
| vec3 h = normalize(v + l); |
| vec3 r = normalize(reflect(direction, n)); |
| |
| float NoV = abs(dot(n, v)) + 1e-5; |
| float NoL = saturate(dot(n, l)); |
| float NoH = saturate(dot(n, h)); |
| float LoH = saturate(dot(l, h)); |
| |
| vec3 baseColor = vec3(0.0); |
| float roughness = 0.0; |
| float metallic = 0.0; |
| |
| float intensity = 2.0; |
| float indirectIntensity = 0.64; |
| |
| if (material < 4.0) { |
| // Checkerboard floor |
| float f = mod(floor(6.0 * position.z) + floor(6.0 * position.x), 2.0); |
| baseColor = 0.4 + f * vec3(0.6); |
| roughness = 0.1; |
| } else if (material < 16.0) { |
| // Metallic objects |
| baseColor = vec3(0.3, 0.0, 0.0); |
| roughness = 0.2; |
| } |
| |
| float linearRoughness = roughness * roughness; |
| vec3 diffuseColor = (1.0 - metallic) * baseColor.rgb; |
| vec3 f0 = 0.04 * (1.0 - metallic) + baseColor.rgb * metallic; |
| |
| float attenuation = shadow(position, l, 0.02, 2.5); |
| |
| // specular BRDF |
| float D = D_GGX(linearRoughness, NoH, h); |
| float V = V_SmithGGXCorrelated(linearRoughness, NoV, NoL); |
| vec3 F = F_Schlick(f0, LoH); |
| vec3 Fr = (D * V) * F; |
| |
| // diffuse BRDF |
| vec3 Fd = diffuseColor * Fd_Burley(linearRoughness, NoV, NoL, LoH); |
| |
| color = Fd + Fr; |
| color *= (intensity * attenuation * NoL) * vec3(0.98, 0.92, 0.89); |
| |
| // diffuse indirect |
| vec3 indirectDiffuse = Irradiance_SphericalHarmonics(n) * Fd_Lambert(); |
| |
| vec2 indirectHit = traceRay(position, r); |
| vec3 indirectSpecular = vec3(0.65, 0.85, 1.0) + r.y * 0.72; |
| if (indirectHit.y > 0.0) { |
| if (indirectHit.y < 4.0) { |
| vec3 indirectPosition = position + indirectHit.x * r; |
| // Checkerboard floor |
| float f = mod(floor(6.0 * indirectPosition.z) + floor(6.0 * indirectPosition.x), 2.0); |
| indirectSpecular = 0.4 + f * vec3(0.6); |
| } else if (indirectHit.y < 16.0) { |
| // Metallic objects |
| indirectSpecular = vec3(0.3, 0.0, 0.0); |
| } |
| } |
| |
| // indirect contribution |
| vec2 dfg = PrefilteredDFG_Karis(roughness, NoV); |
| vec3 specularColor = f0 * dfg.x + dfg.y; |
| vec3 ibl = diffuseColor * indirectDiffuse + indirectSpecular * specularColor; |
| |
| color += ibl * indirectIntensity; |
| } |
| |
| return color; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Setup and execution |
| //------------------------------------------------------------------------------ |
| |
| mat3 setCamera(in vec3 origin, in vec3 target, float rotation) { |
| vec3 forward = normalize(target - origin); |
| vec3 orientation = vec3(sin(rotation), cos(rotation), 0.0); |
| vec3 left = normalize(cross(forward, orientation)); |
| vec3 up = normalize(cross(left, forward)); |
| return mat3(left, up, forward); |
| } |
| |
| void main() { |
| // Normalized coordinates |
| vec2 p = -1.0 + 2.0 * gl_FragCoord.xy / resolution.xy; |
| // Aspect ratio |
| p.x *= resolution.x / resolution.y; |
| |
| // Camera position and "look at" |
| vec3 origin = vec3(0.0, 1.0, 0.0); |
| vec3 target = vec3(0.0); |
| |
| origin.x += 2.0 * cos(time * 0.2); |
| origin.z += 2.0 * sin(time * 0.2); |
| |
| mat3 toWorld = setCamera(origin, target, 0.0); |
| vec3 direction = toWorld * normalize(vec3(p.xy, 2.0)); |
| |
| // Render scene |
| float distance; |
| vec3 color = render(origin, direction, distance); |
| |
| // Tone mapping |
| color = Tonemap_ACES(color); |
| |
| // Exponential distance fog |
| color = mix(color, 0.8 * vec3(0.7, 0.8, 1.0), 1.0 - exp2(-0.011 * distance * distance)); |
| |
| // Gamma compression |
| color = OECF_sRGBFast(color); |
| |
| fragColor = vec4(color, 1.0); |
| } |
| )SHADER__"; |
| |
| static const android::vec3 SPHERICAL_HARMONICS[4] = |
| {{0.754554516862612, 0.748542953903366, 0.790921515418539}, |
| {-0.083856548007422, 0.092533500963210, 0.322764661032516}, |
| {0.308152705331738, 0.366796330467391, 0.466698181299906}, |
| {-0.188884931542396, -0.277402551592231, -0.377844212327557}}; |
| |
| static const android::vec4 TRIANGLE[3] = {{-1.0f, -1.0f, 1.0f, 1.0f}, |
| {3.0f, -1.0f, 1.0f, 1.0f}, |
| {-1.0f, 3.0f, 1.0f, 1.0f}}; |