32 lines
1.3 KiB
Text
32 lines
1.3 KiB
Text
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#version 460
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#extension GL_EXT_ray_tracing : enable
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// RTVolume intersection shader — runs once per AABB the ray enters
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// (VK_RAY_TRACING_SHADER_GROUP_TYPE_PROCEDURAL_HIT_GROUP_KHR). Analytic
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// ray-sphere test: the unit box [-1,1]^3 built by Mesh::BuildProcedural
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// is treated as the bounding volume of a radius-1 sphere centred at the
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// object origin. The object-space ray is NOT normalised (it is
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// worldToObject * worldRay), so the reported t is directly comparable to
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// the world-space ray parameter — solve the quadratic with the general
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// a = dot(d,d) form rather than assuming |d| == 1. Mirrors
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// intersection.wgsl on the WebGPU path.
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hitAttributeEXT vec2 attribs;
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void main() {
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vec3 oc = gl_ObjectRayOriginEXT; // sphere centre is the origin
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vec3 d = gl_ObjectRayDirectionEXT;
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float a = dot(d, d);
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float b = 2.0 * dot(oc, d);
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float c = dot(oc, oc) - 1.0; // radius 1
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float disc = b * b - 4.0 * a * c;
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if (disc < 0.0) return;
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float sq = sqrt(disc);
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float t = (-b - sq) / (2.0 * a); // near root
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if (t < gl_RayTminEXT) t = (-b + sq) / (2.0 * a); // fall back to far root
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if (t < gl_RayTminEXT || t > gl_RayTmaxEXT) return;
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attribs = vec2(0.0);
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reportIntersectionEXT(t, 0u);
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}
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