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/**
* @file sunLightSSAOF.glsl
*
* Copyright (c) 2007-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#extension GL_ARB_texture_rectangle : enable
//class 1 -- no shadow, SSAO only
uniform sampler2DRect depthMap;
uniform sampler2DRect normalMap;
uniform sampler2D noiseMap;
uniform sampler2D lightFunc;
// Inputs
uniform mat4 shadow_matrix[6];
uniform vec4 shadow_clip;
uniform float ssao_radius;
uniform float ssao_max_radius;
uniform float ssao_factor;
uniform float ssao_factor_inv;
varying vec2 vary_fragcoord;
varying vec4 vary_light;
uniform mat4 inv_proj;
uniform vec2 screen_res;
uniform float shadow_bias;
uniform float shadow_offset;
vec4 getPosition(vec2 pos_screen)
{
float depth = texture2DRect(depthMap, pos_screen.xy).a;
vec2 sc = pos_screen.xy*2.0;
sc /= screen_res;
sc -= vec2(1.0,1.0);
vec4 ndc = vec4(sc.x, sc.y, 2.0*depth-1.0, 1.0);
vec4 pos = inv_proj * ndc;
pos /= pos.w;
pos.w = 1.0;
return pos;
}
//calculate decreases in ambient lighting when crowded out (SSAO)
float calcAmbientOcclusion(vec4 pos, vec3 norm)
{
float ret = 1.0;
float dist = dot(pos.xyz,pos.xyz);
if (dist < 64.0*64.0)
{
vec2 kern[8];
// exponentially (^2) distant occlusion samples spread around origin
kern[0] = vec2(-1.0, 0.0) * 0.125*0.125;
kern[1] = vec2(1.0, 0.0) * 0.250*0.250;
kern[2] = vec2(0.0, 1.0) * 0.375*0.375;
kern[3] = vec2(0.0, -1.0) * 0.500*0.500;
kern[4] = vec2(0.7071, 0.7071) * 0.625*0.625;
kern[5] = vec2(-0.7071, -0.7071) * 0.750*0.750;
kern[6] = vec2(-0.7071, 0.7071) * 0.875*0.875;
kern[7] = vec2(0.7071, -0.7071) * 1.000*1.000;
vec2 pos_screen = vary_fragcoord.xy;
vec3 pos_world = pos.xyz;
vec2 noise_reflect = texture2D(noiseMap, vary_fragcoord.xy/128.0).xy;
float angle_hidden = 0.0;
int points = 0;
float scale = min(ssao_radius / -pos_world.z, ssao_max_radius);
// it was found that keeping # of samples a constant was the fastest, probably due to compiler optimizations (unrolling?)
for (int i = 0; i < 8; i++)
{
vec2 samppos_screen = pos_screen + scale * reflect(kern[i], noise_reflect);
vec3 samppos_world = getPosition(samppos_screen).xyz;
vec3 diff = pos_world - samppos_world;
float dist2 = dot(diff, diff);
// assume each sample corresponds to an occluding sphere with constant radius, constant x-sectional area
// --> solid angle shrinking by the square of distance
//radius is somewhat arbitrary, can approx with just some constant k * 1 / dist^2
//(k should vary inversely with # of samples, but this is taken care of later)
//if (dot((samppos_world - 0.05*norm - pos_world), norm) > 0.0) // -0.05*norm to shift sample point back slightly for flat surfaces
// angle_hidden += min(1.0/dist2, ssao_factor_inv); // dist != 0 follows from conditional. max of 1.0 (= ssao_factor_inv * ssao_factor)
angle_hidden = angle_hidden + float(dot((samppos_world - 0.05*norm - pos_world), norm) > 0.0) * min(1.0/dist2, ssao_factor_inv);
// 'blocked' samples (significantly closer to camera relative to pos_world) are "no data", not "no occlusion"
points = points + int(diff.z > -1.0);
}
angle_hidden = min(ssao_factor*angle_hidden/float(points), 1.0);
ret = (1.0 - (float(points != 0) * angle_hidden));
ret += max((dist-32.0*32.0)/(32.0*32.0), 0.0);
}
return min(ret, 1.0);
}
void main()
{
vec2 pos_screen = vary_fragcoord.xy;
//try doing an unproject here
vec4 pos = getPosition(pos_screen);
vec3 norm = texture2DRect(normalMap, pos_screen).xyz*2.0-1.0;
gl_FragColor[0] = 1.0;
gl_FragColor[1] = calcAmbientOcclusion(pos, norm);
gl_FragColor[2] = 1.0;
gl_FragColor[3] = 1.0;
}
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