ludic/packages/ludic.render3d/shaders/tershadow.frag
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feat(gl): OpenGL 4.1 and the ludic.render3d renderer
`Gl.*` binds the whole OpenGL 4.1 core API — every entry point of the
platform gl3.h with every GL_* constant, generated by `ludic-dev glgen`
with per-call ABI thunks. Windowed builds get an NSOpenGLContext on the
existing window at Retina resolution; headless builds render into an
offscreen CGL context, so a program that uses Gl.* renders and
screenshots identically under the test harness. It links gl.ll, the
thunks and OpenGL.framework only when used; every other build stays
byte-identical.

packages/ludic.render3d is a physically based renderer written on that
surface: HDRI image-based lighting, GPU-generated terrain with scanned
PBR materials, CDLOD, cascaded shadows, glTF with skinning, instanced
vegetation with impostors, procedural grass, water, SSAO, and an HDR
pipeline with bloom, auto-exposure and ACES.

It also carries this session's work on it: the terrain at half its cost
(10.3 -> 5.4 ms of frame), the streaming hitch that got worse the longer
you played, a resize that emptied the world, and the packaging that lets
a game use the renderer from its own repository — `ludic assets`, the
material manifest shipping with the package, and shader lookup falling
back to the install root. See changes/ for each, with its numbers.

The camping game that drove all of it has moved out to its own
repository, Maroon Lake; examples/rendering/smooth.ludic stays as the
renderer's example here.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-10 03:31:12 +03:00

39 lines
1.7 KiB
GLSL

// Height-field sun shadow, baked once per sun direction (the sun is fixed per scene).
//
// For every height-map texel: the lowest height at which a point above that texel still
// sees the sun. A point (xz, y) is lit iff the ray toward the sun clears the ground
// everywhere along it, i.e. y > h(xz + d.xz t) - d.y t for all t — so the value stored
// is the maximum of that expression over the ray. Every receiver in the scene (ground,
// trunk, crown, card, water) compares its own height against it: one march per texel,
// once, instead of 28 taps per terrain pixel per frame, and vegetation standing in a
// hillside's shadow goes dark with the hillside instead of glowing in front of it.
// The second channel is the distance to the occluder that set the bound, which widens
// the penumbra the way a real shadow softens with distance from its caster.
in vec2 v_uv;
out vec4 o;
uniform sampler2D u_height;
uniform float u_half;
uniform vec3 u_sun;
void main() {
vec2 xz = (v_uv - 0.5) * 2.0 * u_half;
vec3 d = u_sun;
float lit = -1.0e6;
float at = 0.0;
if (d.y > 0.02) {
float t = 1.5, step = 1.5;
for (int i = 0; i < 128; i++) {
vec2 q = xz + d.xz * t;
vec2 uv = q / (2.0 * u_half) + 0.5;
if (uv.x < 0.0 || uv.x > 1.0 || uv.y < 0.0 || uv.y > 1.0) break;
float h = texture(u_height, uv).r - d.y * t;
if (h > lit) { lit = h; at = t; }
t += step;
step *= 1.045;
}
}
// the cloud layer's mask, once, into B: sampled by cloudShadow() with the sun offset and
// the drift applied as a uv shift, instead of a five-octave fbm in every lit pixel of
// every pass
float cloud = smoothstep(0.02, 0.32, fbm(xz * 0.0011, 5));
o = vec4(lit, at, cloud, 1.0);
}