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// Use functions from this file everywhere a heightmap is used,
// so it is easy to track and change the format
float sample_heightmap(sampler2D spl, vec2 pos) {
// RF
return texture(spl, pos).r;
}
vec4 encode_height_to_viewport(float h) {
//return vec4(encode_height_to_rgb8_unorm(h), 1.0);
// Encode regular floats into an assumed RGBA8 output color.
// This is used because Godot 4.0 doesn't support RF viewports,
// and the irony is, even if float viewports get supported, it's likely it will end up RGBAF,
// which is wasting bandwidth because we are only interested in R...
uint u = floatBitsToUint(h);
return vec4(
float((u >> 0u) & 255u),
float((u >> 8u) & 255u),
float((u >> 16u) & 255u),
float((u >> 24u) & 255u)
) / vec4(255.0);
}
float decode_height_from_viewport(vec4 c) {
uint u = uint(c.r * 255.0)
| (uint(c.g * 255.0) << 8u)
| (uint(c.b * 255.0) << 16u)
| (uint(c.a * 255.0) << 24u);
return uintBitsToFloat(u);
}
float sample_height_from_viewport(sampler2D screen, vec2 uv) {
ivec2 ts = textureSize(screen, 0);
vec2 norm_to_px = vec2(ts);
// Convert to pixels and apply a small offset so we interpolate from pixel centers
vec2 uv_px_f = uv * norm_to_px - vec2(0.5);
ivec2 uv_px = ivec2(uv_px_f);
// Get interpolation pixel positions
ivec2 p00 = uv_px;
ivec2 p10 = uv_px + ivec2(1, 0);
ivec2 p01 = uv_px + ivec2(0, 1);
ivec2 p11 = uv_px + ivec2(1, 1);
// Get pixels
vec4 c00 = texelFetch(screen, p00, 0);
vec4 c10 = texelFetch(screen, p10, 0);
vec4 c01 = texelFetch(screen, p01, 0);
vec4 c11 = texelFetch(screen, p11, 0);
// Decode heights
float h00 = decode_height_from_viewport(c00);
float h10 = decode_height_from_viewport(c10);
float h01 = decode_height_from_viewport(c01);
float h11 = decode_height_from_viewport(c11);
// Linear filter
vec2 f = fract(uv_px_f);
float h = mix(mix(h00, h10, f.x), mix(h01, h11, f.x), f.y);
return h;
}
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