diff options
Diffstat (limited to 'game/addons/zylann.hterrain/shaders/include/heightmap_rgb8_encoding.gdshaderinc')
-rw-r--r-- | game/addons/zylann.hterrain/shaders/include/heightmap_rgb8_encoding.gdshaderinc | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/game/addons/zylann.hterrain/shaders/include/heightmap_rgb8_encoding.gdshaderinc b/game/addons/zylann.hterrain/shaders/include/heightmap_rgb8_encoding.gdshaderinc new file mode 100644 index 0000000..bb30ebe --- /dev/null +++ b/game/addons/zylann.hterrain/shaders/include/heightmap_rgb8_encoding.gdshaderinc @@ -0,0 +1,57 @@ + +const float V2_UNIT_STEPS = 1024.0; +const float V2_MIN = -8192.0; +const float V2_MAX = 8191.0; +const float V2_DF = 255.0 / V2_UNIT_STEPS; + +float decode_height_from_rgb8_unorm_2(vec3 c) { + return (c.r * 0.25 + c.g * 64.0 + c.b * 16384.0) * (4.0 * V2_DF) + V2_MIN; +} + +vec3 encode_height_to_rgb8_unorm_2(float h) { + // TODO Check if this has float precision issues + // TODO Modulo operator might be a performance/compatibility issue + h -= V2_MIN; + int i = int(h * V2_UNIT_STEPS); + int r = i % 256; + int g = (i / 256) % 256; + int b = i / 65536; + return vec3(float(r), float(g), float(b)) / 255.0; +} + +float decode_height_from_rgb8_unorm(vec3 c) { + return decode_height_from_rgb8_unorm_2(c); +} + +vec3 encode_height_to_rgb8_unorm(float h) { + return encode_height_to_rgb8_unorm_2(h); +} + +// TODO Remove for now? +// Bilinear filtering appears to work well enough without doing this. +// There are some artifacts, but we could easily live with them, +// and I suspect they could be easy to patch somehow in the encoding/decoding. +// +// In case bilinear filtering is required. +// This is slower than if we had a native float format. +// Unfortunately, Godot 4 removed support for 2D HDR viewports. They were used +// to edit this format natively. Using compute shaders would force users to +// have Vulkan. So we had to downgrade performance a bit using a technique from the GLES2 era... +float sample_height_bilinear_rgb8_unorm(sampler2D heightmap, vec2 uv) { + vec2 ts = vec2(textureSize(heightmap, 0)); + vec2 p00f = uv * ts; + ivec2 p00 = ivec2(p00f); + + vec3 s00 = texelFetch(heightmap, p00, 0).rgb; + vec3 s10 = texelFetch(heightmap, p00 + ivec2(1, 0), 0).rgb; + vec3 s01 = texelFetch(heightmap, p00 + ivec2(0, 1), 0).rgb; + vec3 s11 = texelFetch(heightmap, p00 + ivec2(1, 1), 0).rgb; + + float h00 = decode_height_from_rgb8_unorm(s00); + float h10 = decode_height_from_rgb8_unorm(s10); + float h01 = decode_height_from_rgb8_unorm(s01); + float h11 = decode_height_from_rgb8_unorm(s11); + + vec2 f = p00f - vec2(p00); + return mix(mix(h00, h10, f.x), mix(h01, h11, f.x), f.y); +} |