stk-code_catmod/data/shaders/ssao.frag
Vincent Lejeune 787866909d SSAO: Do not use trilinear filtering
Normals RTT is not mipmapped and thus bad things happened above a
certain value in the depth buffer because of trilinear filtering.
2014-01-17 23:59:08 +01:00

67 lines
2.2 KiB
GLSL

#version 130
uniform sampler2D normals_and_depth;
uniform mat4 invprojm;
uniform mat4 projm;
uniform vec4 samplePoints[16];
in vec2 uv;
const float strengh = 4.;
const float radius = .4f;
#define SAMPLES 16
const float invSamples = strengh / SAMPLES;
// Found here : http://byteblacksmith.com/improvements-to-the-canonical-one-liner-glsl-rand-for-opengl-es-2-0/
float rand(vec2 co)
{
return fract(sin(dot(co.xy,vec2(12.9898,78.233))) * 43758.5453);
}
void main(void)
{
vec4 cur = texture2D(normals_and_depth, uv);
float curdepth = texture2D(normals_and_depth, uv).a;
vec4 FragPos = invprojm * (2.0f * vec4(uv, curdepth, 1.0f) - 1.0f);
FragPos /= FragPos.w;
// get the normal of current fragment
vec3 norm = normalize(cur.xyz * vec3(2.0) - vec3(1.0));
// Workaround for nvidia and skyboxes
float len = dot(vec3(1.0), abs(cur.xyz));
if (len < 0.2 || curdepth > 0.999) discard;
// Make a tangent as random as possible
vec3 randvect;
randvect.x = rand(uv);
randvect.y = rand(vec2(randvect.x, FragPos.z));
randvect.z = rand(randvect.xy);
vec3 tangent = normalize(cross(norm, randvect));
vec3 bitangent = cross(norm, tangent);
float bl = 0.0;
for(int i = 0; i < SAMPLES; ++i) {
vec3 sampleDir = samplePoints[i].x * tangent + samplePoints[i].y * bitangent + samplePoints[i].z * norm;
sampleDir *= samplePoints[i].w;
vec4 samplePos = FragPos + radius * vec4(sampleDir, 0.0);
vec4 sampleProj = projm * samplePos;
sampleProj /= sampleProj.w;
bool isInsideTexture = (sampleProj.x > -1.) && (sampleProj.x < 1.) && (sampleProj.y > -1.) && (sampleProj.y < 1.);
// get the depth of the occluder fragment
float occluderFragmentDepth = texture2D(normals_and_depth, (sampleProj.xy * 0.5) + 0.5).a;
// Position of the occluder fragment in worldSpace
vec4 occluderPos = invprojm * vec4(sampleProj.xy, 2.0 * occluderFragmentDepth - 1.0, 1.0f);
occluderPos /= occluderPos.w;
bool isOccluded = isInsideTexture && (sampleProj.z > (2. * occluderFragmentDepth - 1.0)) && (distance(FragPos, occluderPos) < radius);
bl += isOccluded ? smoothstep(radius, 0, distance(samplePos, FragPos)) : 0.;
}
// output the result
float ao = 1.0 - bl * invSamples;
gl_FragColor = vec4(ao);
}