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fgdata/Shaders/HDR/aerial_perspective.glsl
Fernando García Liñán 1e66c4104a HDR: Improved environment mapping
- Terrain and clouds and now rendered on the envmap, with correct aerial
  perspective.
- Each face is rendered on a separate frame to help with performance.
- All faces are updated every 1.5 minutes. This can be changed through a
  property.
2023-05-03 02:03:10 +02:00

52 lines
1.6 KiB
GLSL

#version 330 core
uniform sampler2D aerial_perspective_tex;
const float AP_SLICE_COUNT = 32.0;
const float AP_MAX_DEPTH = 128000.0;
const float AP_SLICE_WIDTH_PIXELS = 32.0;
const float AP_SLICE_SIZE = 1.0 / AP_SLICE_COUNT;
const float AP_TEXEL_WIDTH = 1.0 / (AP_SLICE_COUNT * AP_SLICE_WIDTH_PIXELS);
vec4 sample_aerial_perspective_slice(sampler2D lut, vec2 coord, float slice)
{
// Sample at the pixel center
float offset = slice * AP_SLICE_SIZE + AP_TEXEL_WIDTH * 0.5;
float x = coord.x * (AP_SLICE_SIZE - AP_TEXEL_WIDTH) + offset;
return texture(lut, vec2(x, coord.y));
}
vec4 sample_aerial_perspective(sampler2D lut, vec2 coord, float depth)
{
vec4 color;
float w = sqrt(clamp(depth / AP_MAX_DEPTH, 0.0, 1.0));
float x = w * AP_SLICE_COUNT;
if (x <= 1.0) {
// Handle special case of fragments behind the first slice
color = mix(vec4(0.0, 0.0, 0.0, 1.0),
sample_aerial_perspective_slice(lut, coord, 0),
x);
} else {
// Manually interpolate between slices
x -= 1.0;
color = mix(sample_aerial_perspective_slice(lut, coord, floor(x)),
sample_aerial_perspective_slice(lut, coord, ceil(x)),
fract(x));
}
return color;
}
vec4 get_aerial_perspective(vec2 coord, float depth)
{
return sample_aerial_perspective(aerial_perspective_tex, coord, depth);
}
vec3 mix_aerial_perspective(vec3 color, vec4 ap)
{
return color * ap.a + ap.rgb;
}
vec3 add_aerial_perspective(vec3 color, vec2 coord, float depth)
{
return mix_aerial_perspective(color, get_aerial_perspective(coord, depth));
}