Fix GuiTraceRay for radardrift (#1764)

* Introduce GetQuadsOnWideRay and use it for the purposes of tracing along a ray of certain width.

rts/Game/TraceRay.cpp

@@ -421,7 +421,12 @@ float GuiTraceRay(
 	CollisionQuery cq;
 
 	QuadFieldQuery qfQuery;
-	quadField.GetQuadsOnRay(qfQuery, start, dir, maxRayLength);
+	if (useRadar) {
+		const float allyTeamError = losHandler->GetAllyTeamRadarErrorSize(gu->myAllyTeam);
+		quadField.GetQuadsOnWideRay(qfQuery, start, dir, maxRayLength, allyTeamError);
+	} else {
+		quadField.GetQuadsOnRay(qfQuery, start, dir, maxRayLength);
+	}
 
 	for (const int quadIdx: *qfQuery.quads) {
 		const CQuadField::Quad& quad = quadField.GetQuad(quadIdx);

rts/Sim/Misc/QuadField.cpp

@@ -329,6 +329,97 @@ void CQuadField::GetQuadsOnRay(QuadFieldQuery& qfq, const float3& start, const f
 }
 
 
+// Test with wide ray that also extends width at the extremes.
+void CQuadField::GetQuadsOnWideRay(QuadFieldQuery& qfq, const float3& start, const float3& dir, float length, float width)
+{
+	RECOIL_DETAILED_TRACY_ZONE;
+	dir.AssertNaNs();
+	start.AssertNaNs();
+
+	const float3 baseTo = start + (dir * length);
+
+	const bool noZdir = (math::floor(start.z * invQuadSize.y) == math::floor(baseTo.z * invQuadSize.y));
+
+	// special case, prevent div0.
+	if (noZdir) {
+		// Having noZdir will roughly result in a rectangle.
+		float startX = start.x;
+		float finalX = baseTo.x;
+		if (finalX < startX)
+			std::swap(startX, finalX);
+
+		float startZ = start.z;
+		float finalZ = baseTo.z;
+		if (finalZ < startZ)
+			std::swap(startZ, finalZ);
+
+		const float3 mins(startX - width, 0, startZ - width);
+		const float3 maxs(finalX + width, 0, finalZ + width);
+
+		return GetQuadsRectangle(qfq, mins, maxs);
+	}
+
+	auto& queryQuads = *(qfq.quads = tempQuads[qfq.threadOwner].ReserveVector());
+
+	// iterate z-range; compute which columns (x) are touched for each row (z)
+	const float3 normDirPlanar = float3(dir.x, 0.0, dir.z).UnsafeNormalize();  // we already checked for unsafe cases before
+	const float widthFactor = std::abs(normDirPlanar.z / dir.z) * width;
+
+	// Start and stop a bit further to account for width
+	const float3 to = baseTo + dir * widthFactor;
+	length = (to - start).Length();
+
+	// taking normDirPlanar.z since we want perpendicular proportion
+	const float mapMarginX = std::abs(width * normDirPlanar.z);
+
+	// From here on, basically a copy of the same section of GetQuadsOnRay, just here extending
+	// startX and finalX with mapMarginX before converting to quad indexes and pushing each row.
+
+	float startZuc = start.z * invQuadSize.y;
+	float finalZuc =    to.z * invQuadSize.y;
+
+	if (finalZuc < startZuc)
+		std::swap(startZuc, finalZuc);
+
+	const int startZ = std::clamp <int> (startZuc, 0, numQuadsZ - 1);
+	const int finalZ = std::clamp <int> (finalZuc, 0, numQuadsZ - 1);
+
+	assert(finalZ < quadSizeZ);
+
+	const float invDirZ = 1.0f / dir.z;
+
+	for (int z = startZ; z <= finalZ; z++) {
+		float t0 = ((z    ) * quadSizeZ - start.z) * invDirZ;
+		float t1 = ((z + 1) * quadSizeZ - start.z) * invDirZ;
+
+		if ((startZuc < 0 && z == 0) || (startZuc >= numQuadsZ && z == finalZ))
+			t0 = ((startZuc    ) * quadSizeZ - start.z) * invDirZ;
+
+		if ((finalZuc < 0 && z == 0) || (finalZuc >= numQuadsZ && z == finalZ))
+			t1 = ((finalZuc + 1) * quadSizeZ - start.z) * invDirZ;
+
+		t0 = std::clamp(t0, 0.0f, length);
+		t1 = std::clamp(t1, 0.0f, length);
+
+		float mapStartX = dir.x * t0 + start.x;
+		float mapFinalX = dir.x * t1 + start.x;
+
+		if (mapFinalX < mapStartX)
+			std::swap(mapStartX, mapFinalX);
+
+		const unsigned startX = std::clamp <int> ((mapStartX - mapMarginX) * invQuadSize.x, 0, numQuadsX - 1);
+		const unsigned finalX = std::clamp <int> ((mapFinalX + mapMarginX) * invQuadSize.x, 0, numQuadsX - 1);
+
+		const int row = std::clamp(z, 0, numQuadsZ - 1) * numQuadsX;
+
+		for (unsigned x = startX; x <= finalX; x++) {
+			queryQuads.push_back(row + x);
+			assert(static_cast<unsigned>(queryQuads.back()) < baseQuads.size());
+		}
+	}
+}
+
+
 
 #ifndef UNIT_TEST
 bool CQuadField::InsertUnitIf(CUnit* unit, const float3& wpos)

rts/Sim/Misc/QuadField.h

@@ -96,6 +96,7 @@ class CQuadField : spring::noncopyable
 	void GetQuads(QuadFieldQuery& qfq, float3 pos, float radius);
 	void GetQuadsRectangle(QuadFieldQuery& qfq, const float3& mins, const float3& maxs);
 	void GetQuadsOnRay(QuadFieldQuery& qfq, const float3& start, const float3& dir, float length);
+	void GetQuadsOnWideRay(QuadFieldQuery& qfq, const float3& start, const float3& dir, float length, float width);
 
 	void GetUnitsAndFeaturesColVol(
 		const float3& pos,