46 lines
2.0 KiB
HLSL
46 lines
2.0 KiB
HLSL
// Copyright (c) Wojciech Figat. All rights reserved.
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#ifndef __COLLISIONS__
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#define __COLLISIONS__
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bool RayHitSphere(float3 r, float3 sphereCenter, float sphereRadius)
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{
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float3 closestPointOnRay = max(0, dot(sphereCenter, r)) * r;
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float3 centerToRay = closestPointOnRay - sphereCenter;
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return dot(centerToRay, centerToRay) <= (sphereRadius * sphereRadius);
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}
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bool RayHitRect(float3 r, float3 rectCenter, float3 rectX, float3 rectY, float3 rectZ, float rectExtentX, float rectExtentY)
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{
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float3 pointOnPlane = r * max(0, dot(rectZ, rectCenter) / dot(rectZ, r));
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bool inExtentX = abs(dot(rectX, pointOnPlane - rectCenter)) <= rectExtentX;
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bool inExtentY = abs(dot(rectY, pointOnPlane - rectCenter)) <= rectExtentY;
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return inExtentX && inExtentY;
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}
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// Hits axis-aligned box (boxMin, boxMax) with a line (lineStart, lineEnd).
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// Returns the intersections on the line (x - closest, y - furthest).
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// Line hits the box if: intersections.x < intersections.y.
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// Hit point is: hitPoint = lineStart + (lineEnd - lineStart) * intersections.x/y.
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float2 LineHitBox(float3 lineStart, float3 lineEnd, float3 boxMin, float3 boxMax)
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{
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float3 invDirection = 1.0f / (lineEnd - lineStart);
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float3 enterIntersection = (boxMin - lineStart) * invDirection;
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float3 exitIntersection = (boxMax - lineStart) * invDirection;
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float3 minIntersections = min(enterIntersection, exitIntersection);
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float3 maxIntersections = max(enterIntersection, exitIntersection);
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float2 intersections;
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intersections.x = max(minIntersections.x, max(minIntersections.y, minIntersections.z));
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intersections.y = min(maxIntersections.x, min(maxIntersections.y, maxIntersections.z));
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return saturate(intersections);
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}
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// Determines whether there is an intersection between a box and a sphere.
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bool BoxIntersectsSphere(float3 boxMin, float3 boxMax, float3 sphereCenter, float sphereRadius)
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{
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const float3 clampedCenter = clamp(sphereCenter, boxMin, boxMax);
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return distance(sphereCenter, clampedCenter) <= sphereRadius;
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}
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#endif
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