I've followed this tutorial for a custom ray-obb intersection test, but I'm having some trouble with my implementation. I'm not even sure what the behavior is like; from one viewpoint the intersection tests positive all over the screen, but when I move right half a unit it tests false almost everywhere. I'm pretty sure I'm passing in the correct ray, and that the problem lies in the intersection test function. Here it is:

bool TestRayOBBIntersect(glm::vec3 rayOrigin, glm::vec3 rayDir, glm::vec3 aabbMin, glm::vec3 aabbMax, glm::mat4 ModelMat, float& intersectDistance){
float tMinX = 0.0f, tMinY = 0.0f, tMinZ = 0.0f;
float tMaxX = 100000.0f, tMaxY = 100000.0f, tMaxZ = 100000.0f;
float xDist, yDist, zDist;
 
glm::vec3 obbPos = glm::vec3(ModelMat[3].x, ModelMat[3].y, ModelMat[3].z);
glm::vec3 delta = obbPos - rayOrigin;
 
// X axis
glm::vec3 xaxis = glm::vec3(ModelMat[0].x, ModelMat[0].y, ModelMat[0].z);
float e = glm::dot(xaxis, delta);
float f = glm::dot(rayDir, xaxis);
 
float t1 = (e+aabbMin.x)/f;
float t2 = (e+aabbMax.x)/f;
if (t1 > t2){
float w = t1; t1 = t2; t2 = w;
}
if (t2 < tMaxX) tMaxX = t2;
if (t1 > tMinX) tMinX = t1;
if (tMaxX < tMinX) return false;
 
xDist = t1;// Distance to the nearest intersection in x
 
// Y axis
glm::vec3 yaxis = glm::vec3(ModelMat[1].x, ModelMat[1].y, ModelMat[1].z);
float g = glm::dot(yaxis, delta);
float h = glm::dot(rayDir, yaxis);
 
float t3 = (g+aabbMin.y)/h;
float t4 = (g+aabbMax.y)/h;
if (t3 > t4){
float w = t3; t3 = t4; t4 = w;
}
if (t4 < tMaxY) tMaxY = t4;
if (t3 > tMinY) tMinY = t3;
if (tMaxY < tMinY) return false;
 
yDist = t3;// Distance to the nearest intersection in y
 
// Z axis
glm::vec3 zaxis = glm::vec3(ModelMat[2].x, ModelMat[2].y, ModelMat[2].z);
float i = glm::dot(zaxis, delta);
float j = glm::dot(rayDir, zaxis);
 
float t5 = (i+aabbMin.z)/j;
float t6 = (i+aabbMax.z)/j;
if (t5 > t6){
float w = t5; t5 = t6; t6 = w;
}
if (t6 < tMaxZ) tMaxZ = t6;
if (t5 > tMinZ) tMinZ = t5;
if (tMaxZ < tMinZ) return false;
 
zDist = t5;// Distance to the nearest intersection in z
 
intersectDistance = sqrt((xDist*xDist + yDist*yDist + zDist*zDist));// Total distance to nearest intersection
 
return true;
}