godot/drivers/gles3/shaders/screen_space_reflection.glsl
2016-12-02 22:23:16 -03:00

346 lines
8.7 KiB
GLSL

[vertex]
layout(location=0) in highp vec4 vertex_attrib;
layout(location=4) in vec2 uv_in;
out vec2 uv_interp;
out vec2 pos_interp;
void main() {
uv_interp = uv_in;
gl_Position = vertex_attrib;
pos_interp.xy=gl_Position.xy;
}
[fragment]
in vec2 uv_interp;
in vec2 pos_interp;
uniform sampler2D source_diffuse; //texunit:0
uniform sampler2D source_normal_roughness; //texunit:1
uniform sampler2D source_depth; //texunit:2
uniform float camera_z_near;
uniform float camera_z_far;
uniform vec2 viewport_size;
uniform vec2 pixel_size;
uniform float filter_mipmap_levels;
uniform mat4 inverse_projection;
uniform mat4 projection;
uniform int num_steps;
uniform float depth_tolerance;
uniform float distance_fade;
uniform float acceleration;
layout(location = 0) out vec4 frag_color;
vec2 view_to_screen(vec3 view_pos,out float w) {
vec4 projected = projection * vec4(view_pos, 1.0);
projected.xyz /= projected.w;
projected.xy = projected.xy * 0.5 + 0.5;
w=projected.w;
return projected.xy;
}
#define M_PI 3.14159265359
void main() {
////
vec4 diffuse = texture( source_diffuse, uv_interp );
vec4 normal_roughness = texture( source_normal_roughness, uv_interp);
vec3 normal;
normal = normal_roughness.xyz*2.0-1.0;
float roughness = normal_roughness.w;
float depth_tex = texture(source_depth,uv_interp).r;
vec4 world_pos = inverse_projection * vec4( uv_interp*2.0-1.0, depth_tex*2.0-1.0, 1.0 );
vec3 vertex = world_pos.xyz/world_pos.w;
vec3 view_dir = normalize(vertex);
vec3 ray_dir = normalize(reflect(view_dir, normal));
if (dot(ray_dir,normal)<0.001) {
frag_color=vec4(0.0);
return;
}
//ray_dir = normalize(view_dir - normal * dot(normal,view_dir) * 2.0);
//ray_dir = normalize(vec3(1,1,-1));
////////////////
//make ray length and clip it against the near plane (don't want to trace beyond visible)
float ray_len = (vertex.z + ray_dir.z * camera_z_far) > -camera_z_near ? (-camera_z_near - vertex.z) / ray_dir.z : camera_z_far;
vec3 ray_end = vertex + ray_dir*ray_len;
float w_begin;
vec2 vp_line_begin = view_to_screen(vertex,w_begin);
float w_end;
vec2 vp_line_end = view_to_screen( ray_end, w_end);
vec2 vp_line_dir = vp_line_end-vp_line_begin;
//we need to interpolate w along the ray, to generate perspective correct reflections
w_begin = 1.0/w_begin;
w_end = 1.0/w_end;
float z_begin = vertex.z*w_begin;
float z_end = ray_end.z*w_end;
vec2 line_begin = vp_line_begin/pixel_size;
vec2 line_dir = vp_line_dir/pixel_size;
float z_dir = z_end - z_begin;
float w_dir = w_end - w_begin;
// clip the line to the viewport edges
float scale_max_x = min(1, 0.99 * (1.0 - vp_line_begin.x) / max(1e-5, vp_line_dir.x));
float scale_max_y = min(1, 0.99 * (1.0 - vp_line_begin.y) / max(1e-5, vp_line_dir.y));
float scale_min_x = min(1, 0.99 * vp_line_begin.x / max(1e-5, -vp_line_dir.x));
float scale_min_y = min(1, 0.99 * vp_line_begin.y / max(1e-5, -vp_line_dir.y));
float line_clip = min(scale_max_x, scale_max_y) * min(scale_min_x, scale_min_y);
line_dir *= line_clip;
z_dir *= line_clip;
w_dir *=line_clip;
//clip z and w advance to line advance
vec2 line_advance = normalize(line_dir); //down to pixel
float step_size = length(line_advance)/length(line_dir);
float z_advance = z_dir*step_size; // adapt z advance to line advance
float w_advance = w_dir*step_size; // adapt w advance to line advance
//make line advance faster if direction is closer to pixel edges (this avoids sampling the same pixel twice)
float advance_angle_adj = 1.0/max(abs(line_advance.x),abs(line_advance.y));
line_advance*=advance_angle_adj; // adapt z advance to line advance
z_advance*=advance_angle_adj;
w_advance*=advance_angle_adj;
vec2 pos = line_begin;
float z = z_begin;
float w = w_begin;
float z_from=z/w;
float z_to=z_from;
float depth;
vec2 prev_pos=pos;
bool found=false;
//if acceleration > 0, distance between pixels gets larger each step. This allows covering a larger area
float accel=1.0+acceleration;
float steps_taken=0;
for(float i=0;i<num_steps;i++) {
pos+=line_advance;
z+=z_advance;
w+=w_advance;
//convert to linear depth
depth = texture(source_depth, pos*pixel_size).r * 2.0 - 1.0;
depth = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - depth * (camera_z_far - camera_z_near));
depth=-depth;
z_from = z_to;
z_to = z/w;
if (depth>z_to) {
//if depth was surpassed
if (depth<=max(z_to,z_from)+depth_tolerance) {
//check the depth tolerance
found=true;
}
break;
}
steps_taken+=1.0;
prev_pos=pos;
z_advance*=accel;
w_advance*=accel;
line_advance*=accel;
}
if (found) {
float margin_blend=1.0;
vec2 margin = vec2((viewport_size.x+viewport_size.y)*0.5*0.05); //make a uniform margin
if (any(bvec4(lessThan(pos,-margin),greaterThan(pos,viewport_size+margin)))) {
//clip outside screen + margin
frag_color=vec4(0.0);
return;
}
{
//blend fading out towards external margin
vec2 margin_grad = mix(pos-viewport_size,-pos,lessThan(pos,vec2(0.0)));
margin_blend = 1.0-smoothstep(0.0,margin.x,max(margin_grad.x,margin_grad.y));
//margin_blend=1.0;
}
vec2 final_pos;
float grad;
#ifdef SMOOTH_ACCEL
//if the distance between point and prev point is >1, then take some samples in the middle for smoothing out the image
vec2 blend_dir = pos - prev_pos;
float steps = min(8.0,length(blend_dir));
if (steps>2.0) {
vec2 blend_step = blend_dir/steps;
float blend_z = (z_to-z_from)/steps;
vec2 new_pos;
float subgrad=0.0;
for(float i=0.0;i<steps;i++) {
new_pos = (prev_pos+blend_step*i);
float z = z_from+blend_z*i;
depth = texture(source_depth, new_pos*pixel_size).r * 2.0 - 1.0;
depth = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - depth * (camera_z_far - camera_z_near));
depth=-depth;
subgrad=i/steps;
if (depth>z)
break;
}
final_pos = new_pos;
grad=(steps_taken+subgrad)/num_steps;
} else {
#endif
grad=steps_taken/num_steps;
final_pos=pos;
#ifdef SMOOTH_ACCEL
}
#endif
#ifdef REFLECT_ROUGHNESS
vec4 final_color;
//if roughness is enabled, do screen space cone tracing
if (roughness > 0.001) {
///////////////////////////////////////////////////////////////////////////////////////
//use a blurred version (in consecutive mipmaps) of the screen to simulate roughness
float gloss = 1.0-roughness;
float cone_angle = roughness * M_PI * 0.5;
vec2 cone_dir = final_pos - line_begin;
float cone_len = length(cone_dir);
cone_dir = normalize(cone_dir); //will be used normalized from now on
float max_mipmap = filter_mipmap_levels -1;
float gloss_mult=gloss;
float rem_alpha=1.0;
final_color = vec4(0.0);
for(int i=0;i<7;i++) {
float op_len = 2.0 * tan(cone_angle) * cone_len; //oposite side of iso triangle
float radius;
{
//fit to sphere inside cone (sphere ends at end of cone), something like this:
// ___
// \O/
// V
//
// as it avoids bleeding from beyond the reflection as much as possible. As a plus
// it also makes the rough reflection more elongated.
float a = op_len;
float h = cone_len;
float a2 = a * a;
float fh2 = 4.0f * h * h;
radius = (a * (sqrt(a2 + fh2) - a)) / (4.0f * h);
}
//find the place where screen must be sampled
vec2 sample_pos = ( line_begin + cone_dir * (cone_len - radius) ) * pixel_size;
//radius is in pixels, so it's natural that log2(radius) maps to the right mipmap for the amount of pixels
float mipmap = clamp( log2( radius ), 0.0, max_mipmap );
//mipmap = max(mipmap-1.0,0.0);
//do sampling
vec4 sample_color;
{
sample_color = textureLod(source_diffuse,sample_pos,mipmap);
}
//multiply by gloss
sample_color.rgb*=gloss_mult;
sample_color.a=gloss_mult;
rem_alpha -= sample_color.a;
if(rem_alpha < 0.0) {
sample_color.rgb *= (1.0 - abs(rem_alpha));
}
final_color+=sample_color;
if (final_color.a>=0.95) {
// This code of accumulating gloss and aborting on near one
// makes sense when you think of cone tracing.
// Think of it as if roughness was 0, then we could abort on the first
// iteration. For lesser roughness values, we need more iterations, but
// each needs to have less influence given the sphere is smaller
break;
}
cone_len-=radius*2.0; //go to next (smaller) circle.
gloss_mult*=gloss;
}
} else {
final_color = textureLod(source_diffuse,final_pos*pixel_size,0.0);
}
frag_color = vec4(final_color.rgb,pow(clamp(1.0-grad,0.0,1.0),distance_fade)*margin_blend);
#else
frag_color = vec4(textureLod(source_diffuse,final_pos*pixel_size,0.0).rgb,pow(clamp(1.0-grad,0.0,1.0),distance_fade)*margin_blend);
#endif
} else {
frag_color = vec4(0.0,0.0,0.0,0.0);
}
}