godot/drivers/gles3/shaders/screen_space_reflection.glsl
Rémi Verschelde 4a92d2111b
Merge pull request #38954 from puchik/ssr-far-clip
Check if screen space reflection has passed far clip
2020-10-18 20:48:44 +02:00

288 lines
8.3 KiB
GLSL

/* clang-format off */
[vertex]
layout(location = 0) in highp vec4 vertex_attrib;
/* clang-format on */
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;
}
/* clang-format off */
[fragment]
in vec2 uv_interp;
/* clang-format on */
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 curve_fade_in;
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(1.0, 1.0, -1.0));
////////////////
// 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, 0.99 * (1.0 - vp_line_begin.x) / max(1e-5, vp_line_dir.x));
float scale_max_y = min(1.0, 0.99 * (1.0 - vp_line_begin.y) / max(1e-5, vp_line_dir.y));
float scale_min_x = min(1.0, 0.99 * vp_line_begin.x / max(1e-5, -vp_line_dir.x));
float scale_min_y = min(1.0, 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;
float steps_taken = 0.0;
for (int 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;
#ifdef USE_ORTHOGONAL_PROJECTION
depth = ((depth + (camera_z_far + camera_z_near) / (camera_z_far - camera_z_near)) * (camera_z_far - camera_z_near)) / 2.0;
#else
depth = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - depth * (camera_z_far - camera_z_near));
#endif
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) && (-depth < camera_z_far)) {
// check the depth tolerance and far clip
found = true;
}
break;
}
steps_taken += 1.0;
prev_pos = pos;
}
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, vec2(0.0, 0.0)), greaterThan(pos, viewport_size * 0.5)))) {
// clip at the screen edges
frag_color = vec4(0.0);
return;
}
{
//blend fading out towards inner margin
// 0.25 = midpoint of half-resolution reflection
vec2 margin_grad = mix(viewport_size * 0.5 - pos, pos, lessThan(pos, viewport_size * 0.25));
margin_blend = smoothstep(0.0, margin.x * margin.y, margin_grad.x * margin_grad.y);
//margin_blend = 1.0;
}
vec2 final_pos;
float grad;
grad = steps_taken / float(num_steps);
float initial_fade = curve_fade_in == 0.0 ? 1.0 : pow(clamp(grad, 0.0, 1.0), curve_fade_in);
float fade = pow(clamp(1.0 - grad, 0.0, 1.0), distance_fade) * initial_fade;
final_pos = pos;
#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 - 1.0;
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; // opposite 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, fade * margin_blend);
#else
frag_color = vec4(textureLod(source_diffuse, final_pos * pixel_size, 0.0).rgb, fade * margin_blend);
#endif
} else {
frag_color = vec4(0.0, 0.0, 0.0, 0.0);
}
}